Showing 1–50 of 124 results for author: Naqib, S H

High-pressure electride superconductor Li5N for multifunctional applications: A theoretical insight into the physical properties

Authors: M. Abdul Hadi Shah, S. H. Naqib

Abstract: This study aims to unveil the physical properties of multifunctional Li5N electride under high pressure in the range of 150-350 GPa through first principles analysis within the density functional theory. This study aims to unveil the physical properties of multifunctional Li5N electride under high pressure in the range of 150-350 GPa through first principles analysis within the density functional theory. △ Less

Submitted 11 August, 2026; originally announced August 2026.

Topological Electronic States and Phonon Mediated Superconductivity in Ru Based Ternary Pnictides: ZrRuAs and HfRuP

Authors: Jubair Hossan Abir, Tanvir Khan, Tauhidur Rahman, Md. Kamrul Hassan, Sraboni Saha Moly, Mst. Maskura Khatun, Raihana Shams Islam, Saleh Hasan Naqib

Abstract: This study investigates the structural, electronic, mechanical, optical, thermodynamic, and superconducting properties of ZrRuAs and HfRuP. Electronic band structure calculations reveal topological semimetallic behavior in both compounds with several bands crossing the Fermi level. The inclusion of spin orbit coupling lifts band degeneracies in both compounds. The Fermi surface shows both electron… ▽ More This study investigates the structural, electronic, mechanical, optical, thermodynamic, and superconducting properties of ZrRuAs and HfRuP. Electronic band structure calculations reveal topological semimetallic behavior in both compounds with several bands crossing the Fermi level. The inclusion of spin orbit coupling lifts band degeneracies in both compounds. The Fermi surface shows both electron and hole segments. The estimated Pugh ratio, Poisson ratio and machinability index indicate that both compounds are ductile in nature and exhibit excellent machinability. Optical results show metallic reflectivity and notable absorption in the ultraviolet region. Thermodynamic analysis indicates stable behavior. The estimated superconducting transition temperatures are 9.75 K for ZrRuAs and 9.03 K for HfRuP that indicates strong coupling conventional superconductivity. The results provide a detailed view of the physical and superconducting properties of ZrRuAs and HfRuP and help to close the existing research gaps in these topological superconducting materials. △ Less

Submitted 6 July, 2026; originally announced July 2026.

Electronic Structure, Optical Response, Thermal and Mechanical Behavior of B6X (X = S, Se) under Pressure: A Comprehensive Ab-initio Exploration

Authors: Sourav Kumar Sutradhar, Tanvir Khan, Tauhidur Rahman, Sraboni Saha Moly, Mst. Maskura Khatun, S. H. Naqib

Abstract: This study presents a comprehensive investigation of the pressure dependent structural, electronic, optical, mechanical, and bonding properties of orthorhombic boron rich chalcogenides B6S and B6Se. Calculations were performed using density functional theory across a wide range of hydrostatic pressures. The computed elastic constants, bulk, Young, shear moduli, and Poisson ratio, revealed mechanic… ▽ More This study presents a comprehensive investigation of the pressure dependent structural, electronic, optical, mechanical, and bonding properties of orthorhombic boron rich chalcogenides B6S and B6Se. Calculations were performed using density functional theory across a wide range of hydrostatic pressures. The computed elastic constants, bulk, Young, shear moduli, and Poisson ratio, revealed mechanical robustness and strong resistance to deformation, even under significant compression. Electronic band structure and density of states analyses indicate that the materials exhibit indirect bandgap semiconducting behavior. Optical results reveal clear pressure induced spectral shifts, particularly in the visible and ultraviolet regions, suggesting modified light matter interaction under compression. Phonon dispersion curves verified the dynamical stability of both materials within the investigated pressure range. Hardness estimations, combined with elastic parameters, and melting temperatures, further indicate that B6S and B6Se possess significant mechanical strength suitable for applications under harsh environments. The thermal properties suggest that both these compounds possess features suitable to be used as excellent thermal barrier coating materials. △ Less

Submitted 5 July, 2026; originally announced July 2026.

First-Principles Study of Novel Lead-Free Double Perovskite \b{eta}2SnGeX6 (\b{eta} = K, Rb; X = Cl, Br, I) for thermomechanical, optoelectronic and outstanding thermoelectric applications

Authors: Jubair Hossan Abir, Tauhidur Rahman, S. S. B. Pallab, Md. Sharear Aman, R. S. Islam, S. H. Naqib

Abstract: In this study, the structural, mechanical, electronic, optical, and thermoelectric properties of the novel lead-free halide double perovskite series beta2SnGeX6 (beta = K, Rb; X = Cl, Br, I) are systematically investigated using density functional theory (DFT). Calculated formation energies, Tolerance factors, and octahedral factors confirm that all six compounds exhibit robust thermodynamic stabi… ▽ More In this study, the structural, mechanical, electronic, optical, and thermoelectric properties of the novel lead-free halide double perovskite series beta2SnGeX6 (beta = K, Rb; X = Cl, Br, I) are systematically investigated using density functional theory (DFT). Calculated formation energies, Tolerance factors, and octahedral factors confirm that all six compounds exhibit robust thermodynamic stability within a highly symmetric cubic geometry. Mechanical analysis derived from elastic parameters characterizes the entire series as fundamentally ductile, ensuring high processing elasticity and resistance to micro-cracking during device manufacturing. Electronic band structures reveal direct bandgaps showing exceptional composition-dependent tunability from 1.44 eV down to 0.64 eV via progressive halogen substitution. The wide gap chloride variations are optimized for single-junction photovoltaic absorbers, while the narrower-gap bromide and iodide analogs show immense promise for tandem solar architectures and near-infrared photodetectors. Thermoelectrically, heavy constituent atoms introduce strong lattice anharmonicity and intense high-temperature Umklapp phonon scattering, significantly suppressing lattice thermal conductivity. Combined with low carrier effective masses that optimize electrical transport, the iodide compounds achieve higher power factors and outstanding dimensionless figures of merit (ZT = 2.4 for K2SnGeI6 at 1000 K). Ultimately, these lead-free double perovskite family emerges as an environmentally benign and versatile platform for next-generation green optoelectronics and solid-state waste-heat recovery. △ Less

Submitted 17 June, 2026; originally announced June 2026.

Ambient and Pressure Dependent Superconductivity with Hydrogen Storage Potential in Quaternary Hydride LiMgZr2H12: A Comprehensive First-principles Insights

Authors: Jubair Hossan Abir, Tauhidur Rahman, Salauddin Muhammad Anis, Saleh Hasan Naqib, Raihana Shams Islam

Abstract: Molecular hydrides have attracted relatively less attention in the search for high Tc superconductors because their hydrogen quasi-molecular units tend to be electronically inactive for superconductivity. In contrast, hydrogen rich compounds under high pressure have been widely considered strong candidates for achieving room-temperature superconductivity. However, their dependence on extreme press… ▽ More Molecular hydrides have attracted relatively less attention in the search for high Tc superconductors because their hydrogen quasi-molecular units tend to be electronically inactive for superconductivity. In contrast, hydrogen rich compounds under high pressure have been widely considered strong candidates for achieving room-temperature superconductivity. However, their dependence on extreme pressure conditions significantly constrains their practical applicability. This work investigates hydrogen-rich superconducting materials that may be stable under ambient pressure conditions. Motivated by recent studies on the MgZrH2n family, a LiMgZr2H12 structure with Pmmm symmetry was designed. The mechanical, thermodynamic, and dynamical stability of the compound, together with its electronic and optical properties, were systematically investigated using first-principles calculations. Li doping in LiMgZr2H12 significantly increases the hydrogen derived contribution near the Fermi level (EF) and strengthens the electron-phonon coupling constant (λ) compared with MgZrH6. LiMgZr2H12 exhibits a critical temperature of 72.76 K at ambient pressure, which is further enhanced by applying pressure. At 10 GPa the critical temperature increases to 77.3 K. Elastic property analysis shows that the material remains mechanically stable over the pressure range studied (0-10 GPa). It also behaves like a ductile material suitable for current carrying applications. The material has a high machinability index, which is much higher than that of stainless steels. In addition, LiMgZr2H12 exhibits a gravimetric hydrogen storage capacity of 5.36 wt%, indicating its potential as a promising candidate for hybrid hydrogen storage technologies. This work offers a new direction for designing high-Tc hydrides at ambient conditions. △ Less

Submitted 10 June, 2026; originally announced June 2026.

Physical properties of transition metal hydride superconductors Mg2TmH6 (Tm = Rh, Pd, Ir, Pt) by first-principles calculations

Authors: Md Ashraful Alam, Md Abdul Hadi Shah, F. Parvin, S. H. Naqib

Abstract: In this work, a comprehensive first-principles investigation of the structural, hydrogen storage potential, electronic, elastic, mechanical, thermophysical, superconducting, and optical properties of Mg2TmH6 (Tm = Rh, Pd, Ir, Pt) hydrides is presented. Obtained results demonstrate that Mg2TmH6 hydrides combine favorable hydrogen storage, mechanical robustness, superconductivity, and multifunctiona… ▽ More In this work, a comprehensive first-principles investigation of the structural, hydrogen storage potential, electronic, elastic, mechanical, thermophysical, superconducting, and optical properties of Mg2TmH6 (Tm = Rh, Pd, Ir, Pt) hydrides is presented. Obtained results demonstrate that Mg2TmH6 hydrides combine favorable hydrogen storage, mechanical robustness, superconductivity, and multifunctional optical properties, making them promising candidates for energy storage, superconducting and advanced optoelectronic applications. △ Less

Submitted 28 April, 2026; originally announced April 2026.

First-Principles Investigation of the Pressure Dependent Physical Properties of Intermetallic Kagome ZrRe2

Authors: Mst. Irin Naher, A. F. M. Yusuf Haider, Dholon Kumar Paul, Md Lutfor Rahman, Firoze H. Haque, Saleh Hasan Naqib

Abstract: We present a density functional theory investigation of the pressure dependent structural, electronic, mechanical, thermophysical, vibrational, and optical properties of the intermetallic Kagome compound ZrRe2. The calculated ground-state structural parameters are in excellent agreement with available experimental results. The estimated structural parameters, elastic constants, and phonon dispersi… ▽ More We present a density functional theory investigation of the pressure dependent structural, electronic, mechanical, thermophysical, vibrational, and optical properties of the intermetallic Kagome compound ZrRe2. The calculated ground-state structural parameters are in excellent agreement with available experimental results. The estimated structural parameters, elastic constants, and phonon dispersion confirm the structural, chemical, mechanical, and dynamical stability of ZrRe2 up to 25 GPa. The Kagome feature in the material has been identified from the electronic band structure for the first time. ZrRe2 exhibits topological feature at 0 GPa, which vanishes under 25 GPa. Fermi surface (FS) analysis predicts that ZrRe2 could potentially host a charge density wave (CDW) phase. The electronic and optical studies confirmed its metallic nature. The Debye temperature and phonon thermal conductivity are moderate, while the melting point is relatively high. Furthermore, ZrRe2 possesses moderate electron-phonon coupling, which weakens under pressure as the phonon modes harden. Consequently, the superconducting transition temperature decreases with increasing pressure. Most of the properties studied and analyses performed in this paper are novel in nature. △ Less

Submitted 17 March, 2026; originally announced March 2026.

Pressure dependent topological, superconducting, optoelectronic and thermophysical properties of Ta2Se chalcogenide: Theoretical insights

Authors: Tauhidur Rahman, Jubair Hossan Abir, Sourav Kumar Sutradhar, Sraboni Saha Moly, Mst. Maskura Khatun, Md. Asif Afzal, Saleh Hasan Naqib

Abstract: Tetragonal Ta2Se is a layered, Ta-rich chalcogenide that departs from conventional MX2 transition-metal dichalcogenides by hosting dense Ta-Ta networks capped by Se square-net layers. Here, we present a unified first-principles investigation of hydrostatic-pressure tuning in Ta2Se from 0 to 10 GPa, connecting the structural response, mechanical stability, thermophysical indicators, bonding evoluti… ▽ More Tetragonal Ta2Se is a layered, Ta-rich chalcogenide that departs from conventional MX2 transition-metal dichalcogenides by hosting dense Ta-Ta networks capped by Se square-net layers. Here, we present a unified first-principles investigation of hydrostatic-pressure tuning in Ta2Se from 0 to 10 GPa, connecting the structural response, mechanical stability, thermophysical indicators, bonding evolution, electronic and optical behavior, lattice dynamics and superconductivity within a single framework. The derived thermophysical descriptors corroborate a pressure-stiffened lattice: density increases, Debye temperature rises, melting temperature is elevated and minimum thermal conductivity increases, whereas the Grüneisen parameter remains within a narrow window, suggesting no anomalous anharmonic softening. Bond population metrics and electron-density-difference analysis revealed a mixed metallic-covalent bonding picture dominated by a robust Ta-Ta metallic backbone, accompanied by pressure-strengthened Ta-Se hybridization. Electronic-structure calculations show persistent metallicity under compression; pressure broadens bands, reduces density of states at the Fermi level, reshapes the Fermi surface and points to a possible Lifshitz-type reconstruction without symmetry breaking. The optical response remained metallic with Drude-like low-energy behavior and pressure-tunable spectral features. The phonon dispersions exhibit no imaginary modes, confirming dynamical stability. Electron-phonon coupling calculations classify Ta2Se as a weak-coupling, phonon-mediated superconductor with Tc around 3.9 K, consistent with available experiments and establish pressure as a practical control knob for stability and superconductivity-relevant descriptors in this metal-rich layered platform. △ Less

Submitted 10 February, 2026; originally announced February 2026.

Exploring the Physical Properties, Hydrogen Storage Capacity and Thermal Barrier Performance of LaMg2H7: A First-Principles Investigation

Authors: Tanvir Khan, Md Hasan Shahriar Rifat, M. Ibrahim, J. H. Abir, Saptak Roy, S. H. Naqib

Abstract: LaMg2H7 is a ternary wide band gap semiconductor that is a member of the hydride family. The bulk physical characteristics of the LaMg2H7 compound, including its structural, electronic band structure, elastic, thermal, and optical characteristics, have been examined in this work utilizing density functional theory (DFT). The elastic constants indicate that {\rm LaMg}_2H_7 is mechanically stable, b… ▽ More LaMg2H7 is a ternary wide band gap semiconductor that is a member of the hydride family. The bulk physical characteristics of the LaMg2H7 compound, including its structural, electronic band structure, elastic, thermal, and optical characteristics, have been examined in this work utilizing density functional theory (DFT). The elastic constants indicate that {\rm LaMg}_2H_7 is mechanically stable, brittle in nature, and anisotropic. This studied compound possesses a moderate level of hardness. The band structure and density of states have been examined to have a better understanding of its electronic behavior. The intrinsic carrier concentrations and effective masses have been determined using the band structure. The gravimetric hydrogen storage capacity (Cwt%) has been calculated, indicating that this compound is suitable for hydrogen storage applications. This compound is dynamically stable, as confirmed by its phonon dispersion. Here, the details of this wide-band-gap semiconductor's reflectivity, absorption coefficient, refractive index, dielectric function, optical conductivity, and loss function are investigated. The substance is a moderate reflector of ultraviolet (UV) light. The absorption and conductivity support the gap in the band structure. The thermodynamic properties, such as bulk modulus, internal energy, specific heat capacity, entropy, thermal expansion coefficient, and Debye temperature, have been explored at varying temperatures and pressures. {\rm LaMg}_2H_7 has a moderate level of melting temperature with higher lattice thermal conductivity. The value of the thermal expansion coefficient and minimum thermal conductivity is highly recommended for use as a thermal barrier coating (TBC). △ Less

Submitted 8 May, 2026; v1 submitted 8 October, 2025; originally announced October 2025.

Comments: 31 pages, 8 figures

Ab-initio Study of Structural, Magnetic, Optoelectronic and Thermo-Physical Properties of HoPdBi Half-Heusler Semimetal

Authors: Tanvir Khan, F. Parvin, S. H. Naqib

Abstract: In this investigation, we have used the density functional theory (DFT) to investigate several aspects of the half-Heusler compound HoPdBi. The following properties have been studied: spin polarized electronic properties, magnetic moment, phonon dispersion with phonon density of states, structural, elastic properties, optical characteristics, and thermo-physical features. The calculated unit cell… ▽ More In this investigation, we have used the density functional theory (DFT) to investigate several aspects of the half-Heusler compound HoPdBi. The following properties have been studied: spin polarized electronic properties, magnetic moment, phonon dispersion with phonon density of states, structural, elastic properties, optical characteristics, and thermo-physical features. The calculated unit cell volume and ground-state lattice characteristics closely match the experimental results. This study is the first to examine the optoelectronic, thermo-physical, and elastic characteristics of HoPdBi. The mechanical stability requirements were met by the calculated elastic constants. The compound's ductility is shown by the estimated Pugh's ratio, Poisson's ratio, and Cauchy pressure. Band structures and electronic energy density of states have been evaluated in order to better understand the magnetic features with spin polarization. Band structure simulations were conducted with and without the spin-orbit coupling (SOC) effect in order to look into any topological signature. The electrical band structure of the compound shows semi-metallic properties. The reflectivity, absorption coefficient, refractive index, dielectric function, optical conductivity, and loss function of this semi-metal have all been thoroughly examined. The compound is a good reflector in infrared region and a good absorber of ultraviolet (UV) light. This compound is a suitable candidate for high temperature applications and possesses potential as heat sink because of its high melting point and thermal conductivity. It is also suitable for spintronics applications. The majority of this study's findings are completely novel. △ Less

Submitted 31 May, 2025; originally announced June 2025.

DFT based comparative study of the physical properties of MAlB (M = V, Ta, Mo, Nb) MAB compounds

Authors: Jahid Hassan, M. A. Masum, Ruman Ali, Md. Enamul Haque, S. H. Naqib

Abstract: MAB phases have appealing physical features that make them appropriate for a wide range of applications. Motivated by this, we present density functional theory (DFT) calculations of the structural, elastic, bonding, electronic band dispersion, acoustic behavior, phonon spectrum, various thermomechanical and optoelectronic properties of VAlB and TaAlB ternary borides for the first time. The comput… ▽ More MAB phases have appealing physical features that make them appropriate for a wide range of applications. Motivated by this, we present density functional theory (DFT) calculations of the structural, elastic, bonding, electronic band dispersion, acoustic behavior, phonon spectrum, various thermomechanical and optoelectronic properties of VAlB and TaAlB ternary borides for the first time. The computed ground state lattice parameters of both compounds are very consistent with experimental data. The formation enthalpy, elastic constants, and phonon dispersion calculations indicate that both compounds are chemically, mechanically, and dynamically stable, respectively. The physical parameters of VAlB and TaAlB are studied and compared with those of MoAlB and NbAlB MAB compounds. △ Less

Submitted 2 May, 2025; originally announced May 2025.

DFT based insights into elastic, thermophysical, electronic and optical properties of topological insulators XTe5 (X = Zr, Hf)

Authors: Syed Shovon Mahbub Mahin, Suptajoy Barua, B. Rahman Rano, Ishtiaque M. Syed, S. H. Naqib

Abstract: Transition metal penta-tellurides, ZrTe5 and HfTe5 have been recently drawn a lot of attention due to their fascinating physical properties and for being prominent materials showing topological phase transitions. In this study, we investigated mechanical, thermophysical and optoelectronic properties of these materials which remained almost unexplored till now. We also studied electronic properties… ▽ More Transition metal penta-tellurides, ZrTe5 and HfTe5 have been recently drawn a lot of attention due to their fascinating physical properties and for being prominent materials showing topological phase transitions. In this study, we investigated mechanical, thermophysical and optoelectronic properties of these materials which remained almost unexplored till now. We also studied electronic properties and compared those with previous studies. We used Density Functional Theory (DFT) based calculations to study all of these properties. This study suggests that the materials are mechanically stable, possess high mechanical and bonding anisotropy and are brittle in nature. Our study also suggests that the compounds are soft in nature and they contain a mixture of covalent and metallic bonding. Investigation of thermophysical properties, namely, Grüneisen parameter and Debye temperature indicates weak bonding strength in these compounds. Analysis of melting temperature, thermal expansion coefficient, heat capacity, radiation factor, acoustic impedance, and minimum thermal conductivity suggests their possible application in acoustic and thermoelectric devices. Examination of their optical characteristics reveals that they have a considerable reflectivity from the infrared to the ultraviolet region. The refractive indices of these materials are high at low energy so they are potential candidates for reflective coating of solar radiation. There have been debates over exact topological natures of these compounds, whether they are semi-metals or insulators. Our study of electronic band structure and density of states reveal that spin-orbit interaction is responsible for enhancing energy gaps and promoting insulating characteristics in these compounds. △ Less

Submitted 22 April, 2025; originally announced April 2025.

DFT exploration of pressure dependent physical properties of the recently discovered La3Ni2O7 superconductor

Authors: Md. Enamul Haque, Ruman Ali, M. A. Masum, Jahid Hassan, S. H. Naqib

Abstract: The recent discovery of superconductivity in Ruddlesden-Popper bilayer nickelate La3Ni2O7 under pressure has drawn a lot of interest. La3Ni2O7 is isostructural with cuprates in some respect. Investigation of its properties will undoubtedly provide new insights into high-Tc superconductivity. In the present work, we study structural, mechanical, elastic, optoelectronic, thermophysical properties, a… ▽ More The recent discovery of superconductivity in Ruddlesden-Popper bilayer nickelate La3Ni2O7 under pressure has drawn a lot of interest. La3Ni2O7 is isostructural with cuprates in some respect. Investigation of its properties will undoubtedly provide new insights into high-Tc superconductivity. In the present work, we study structural, mechanical, elastic, optoelectronic, thermophysical properties, and Fermi surface topology of La3Ni2O7 under pressure within the range of 30-40 GPa employing the density functional theory (DFT). The calculated structural parameters agree well with the earlier experimental findings. The structural, mechanical, and thermodynamical stability is justified across the entire pressure range. The computed elastic moduli classify the compound as ductile, and the material's ductility is largely unaffected by pressure. The compound has a high level of machinability index and dry lubricity. The electronic band structure reveals metallic feature of La3Ni2O7. The Debye temperature, thermal conductivity, and melting temperature increase with increasing pressure, but in an anomalous manner. The characteristic peaks in refractive index, reflectivity, and photoconductivity exhibit a small shift towards higher energy for all polarizations of the electric field vector with increasing pressure. The investigated material might be a good ultraviolet radiation absorber and can be used as an anti-reflection system. Moreover, the pressure dependent electronic density of states at the Fermi level, pressure induced negligible variations in the repulsive Coulomb pseudopotential, and the changes in the Debye temperature have been used to explore the effect of pressure on the superconducting transition temperature in this study. △ Less

Submitted 22 April, 2025; originally announced April 2025.

Pressure dependent ab initio study of the physical properties of hexagonal BeB2C: a possible high-Tc superconductor

Authors: Ruman Ali, Md. Enamul Haque, Jahid Hassan, M. A. Masum, R. S. Islam, S. H. Naqib

Abstract: This study uses the Density Functional Theory to explore the pressure dependent properties of hexagonal BeB2C. The metallic nature of BeB2C was substantiated at ambient pressure, with pressure induced alterations in electronic band structure and Fermi surface topology suggesting a potential for tunability across various applications. The phonon dispersion and phonon density of states show the dyna… ▽ More This study uses the Density Functional Theory to explore the pressure dependent properties of hexagonal BeB2C. The metallic nature of BeB2C was substantiated at ambient pressure, with pressure induced alterations in electronic band structure and Fermi surface topology suggesting a potential for tunability across various applications. The phonon dispersion and phonon density of states show the dynamical stability under pressure. The thermophysical properties are also investigated under varying pressure conditions. Finally, the exploration of superconducting properties found that the transition temperature is in good agreement with previously reported values, and illustrated that beB2C holds considerable promise as a high-temperature superconductor, with pressure augmenting its superconducting properties. △ Less

Submitted 18 April, 2025; originally announced April 2025.

DFT based comparative analysis of physical properties of binary metallic diborides XB$_2$ (X = Cr, Mo and W)

Authors: Razu Ahmed, Md. Sohel Rana, Md. Sajidul Islam, S. H. Naqib

Abstract: Transition-metal borides (TMBs) have long attracted attention of the researchers because of their unique mechanical and electrical properties including superconductivity. We have explored the structural, mechanical, electronic, optical, and some thermophysical properties of XB$_2$ (X = Cr, Mo and W) binary metallic diborides in detail employing density functional theory based first-principles meth… ▽ More Transition-metal borides (TMBs) have long attracted attention of the researchers because of their unique mechanical and electrical properties including superconductivity. We have explored the structural, mechanical, electronic, optical, and some thermophysical properties of XB$_2$ (X = Cr, Mo and W) binary metallic diborides in detail employing density functional theory based first-principles method. Many of the physical properties, including direction-dependent mechanical properties, optical properties, and thermo-mechanical properties are being investigated for the first time. △ Less

Submitted 27 December, 2024; originally announced December 2024.

Investigation of the Pressure Dependent Physical Properties of MAX Phase Ti2AlX (X = B, C, and N) Compounds: A First-Principles Study

Authors: M. I. Naher, M. Montasir, M. Y. H. Khan, M. A. Ali, M. M. Hossain, M. M. Uddin, M. Z. Hasan, M. A. Hadi, S. H. Naqib

Abstract: The physical properties and their pressure dependence of recently synthesized Ti2AlX (X = B, C, and N) MAX phases are investigated for the very first time applying density functional theory (DFT). The physical properties and their pressure dependence of recently synthesized Ti2AlX (X = B, C, and N) MAX phases are investigated for the very first time applying density functional theory (DFT). △ Less

Submitted 26 December, 2024; originally announced December 2024.

DFT exploration of novel direct band gap semiconducting halide double perovskites, A2AgIrCl6 (A = Cs, Rb, K), for solar cells application

Authors: M. A. Rayhan, M. M. Hossain, M. M. Uddin, S. H. Naqib, M. A Ali

Abstract: Double perovskite halides are promising materials for renewable energy production, meeting the criteria to address energy scarcity issues. As a result, studying these halides could be useful for optoelectronic and solar cell applications. In this study, we investigated the structural, mechanical, thermodynamic, electronic, and optical properties of A2AgIrCl6 (A = Cs, Rb, K) double perovskite halid… ▽ More Double perovskite halides are promising materials for renewable energy production, meeting the criteria to address energy scarcity issues. As a result, studying these halides could be useful for optoelectronic and solar cell applications. In this study, we investigated the structural, mechanical, thermodynamic, electronic, and optical properties of A2AgIrCl6 (A = Cs, Rb, K) double perovskite halides using density functional theory calculations with the full-potential linearized augmented plane-wave (FP-LAPW) approach, aiming to evaluate their suitability for renewable energy devices. The Goldsmith tolerance factor, octahedral factor, and new tolerance factor have confirmed the cubic stability of the predicted compounds. We have also verified the thermodynamic stability of these compounds by calculating the formation enthalpy, binding energy, and phonon dispersion curves. Additionally, Born-Huang stability requirements on stiffness constants confirmed the mechanical stability of the titled compounds. To predict the accurate optoelectronic properties, we employed the TB-mBJ potential. The electronic band structure calculations revealed that the titled halides exhibit a direct band gap semiconducting nature with values of 1.43 eV, 1.50 eV, and 1.55 eV for Cs2AgIrCl6, Rb2AgIrCl6, and K2AgIrCl6, respectively. Besides, all these compounds showed remarkably low effective electron masses, indicating their potential for high carrier mobility. Furthermore, the optical properties of A2AgIrCl6 (A = Cs, Rb, K) compounds demonstrated very low reflectivity and excellent light absorption coefficients (105 cm-1) in the visible light spectrum, suggesting their suitability as an absorbing layer in solar cells. The photoconductivity and absorption spectra of these compounds validate the accuracy of our band structure results. △ Less

Submitted 17 October, 2024; originally announced October 2024.

Comments: 38 pages

First-principles exploration of the pressure dependent physical properties of Sn4Au: a superconducting topological semimetal

Authors: M. Abdul Hadi Shah, M. I. Naher, S. H. Naqib

Abstract: First-principles investigation within the density functional theory is utilized to explore the physical properties of a superconducting topological semimetal Sn4Au under pressure within the range of 0-5 GPa. According to the computed elastic moduli, the compound under study is classified as ductile and applied pressure enhances the ductility. The compound has very high level of dry lubricity and m… ▽ More First-principles investigation within the density functional theory is utilized to explore the physical properties of a superconducting topological semimetal Sn4Au under pressure within the range of 0-5 GPa. According to the computed elastic moduli, the compound under study is classified as ductile and applied pressure enhances the ductility. The compound has very high level of dry lubricity and machinability index. All the anisotropy factors demonstrate an elastically anisotropic nature. The electronic properties are investigated in view of the electronic band structure and density of states. The band structure reveals the topological semimetallic feature of Sn4Au while the density of states at the Fermi level decreases gradually with increasing pressure. Both ionic and covalent bondings are observed in Sn4Au. Optical parameters of Sn4Au are investigated at different pressures. The characteristic peaks in reflectivity, refractive index and photoconductivity exhibit a shift towards higher energy with increasing pressure for all polarizations of the electric field vector. The absorption coefficient and reflectivity spectra designate Sn4Au as a suitable system for optoelectronic applications. Moreover, the pressure dependent shifts in the electronic density of states at the Fermi level, the changes in the Debye temperature, and pressure induced variations in the repulsive Coulomb pseudopotential have been used to explore the effect of pressure on the superconducting transition temperature in this study. △ Less

Submitted 14 August, 2024; originally announced August 2024.

First-principles investigation of the physical properties of wide band gap hexagonal AlPO4 compound for possible applications

Authors: A. S. M. Muhasin Reza, Md. Asif Afzal, S. H. Naqib

Abstract: In this study, using the density functional theory, we have investigated the bulk physical properties like structural, electronic band structure, elastic properties, thermal properties, optical properties and bonding features of AlPO4 compound in the hexagonal form. The values of our optimized structural parameters are very close to the previous results. Most of the results presented in this work… ▽ More In this study, using the density functional theory, we have investigated the bulk physical properties like structural, electronic band structure, elastic properties, thermal properties, optical properties and bonding features of AlPO4 compound in the hexagonal form. The values of our optimized structural parameters are very close to the previous results. Most of the results presented in this work are novel. The elastic constants indicate that AlPO4 is mechanically stable and brittle in nature. The compound is moderately hard and possesses low machinability index. AlPO4 contains significant elastic anisotropy. The charge density distribution , bond population analysis, Vickers hardness, thermo-mechanical properties, and optical properties have been investigated for the first time. The electronic band structure calculations reveal clear insulating behavior with a band gap of 6.0 eV. Band structure calculations were carried out without and with spin-orbit coupling (SOC) to explore possible topological signature. The energy dependent optical properties conform to the electronic band structure calculations. Major optical properties like dielectric functions, refractive index, photoconductivity, absorption coefficient, loss function and reflectivity are calculated and discussed in detail in this study. The compound is optically anisotropic. It is an efficient absorber and reflector of the ultraviolet light. △ Less

Submitted 26 July, 2024; originally announced July 2024.

A detailed first-principles study of the structural, elastic, thermomechanical and optoelectronic properties of binary rare-earth tritelluride NdTe3

Authors: Tanbin Chowdhury, B. Rahman Rano, Ishtiaque M. Syed, S. H. Naqib

Abstract: Rare-earth tritellurides (RTe3) are popular for their charge density wave (CDW) phase, magnetotransport properties and pressure induced superconducting state among other features. In this literature, Density functional theory has been exploited to study various properties of NdTe3. The calculated elastic and thermomechanical parameters, which were hitherto untouched for any RTe3, uncover soft, duc… ▽ More Rare-earth tritellurides (RTe3) are popular for their charge density wave (CDW) phase, magnetotransport properties and pressure induced superconducting state among other features. In this literature, Density functional theory has been exploited to study various properties of NdTe3. The calculated elastic and thermomechanical parameters, which were hitherto untouched for any RTe3, uncover soft, ductile, highly machinable and damage tolerant characteristics, as well as highly anisotropic mechanical behavior of this layered compound. Its thermomechanical properties make it a prospective thermal barrier coating material. Band structure, density of states, Fermi surfaces and various optical functions of the material have been reported. The band structure demonstrates highly directional metallic nature. The highly dispersive bands indicate very low effective charge carrier mass for the in-plane directions. The Fermi surfaces display symmetric pockets, including signs of nesting, bilayer splitting among others, corroborating previous works. The optical spectra expose high reflectivity across the visible region, while absorption is high in the ultraviolet region. Two plasma frequencies are noticed in the optical loss function. The optical conductivity, reflectivity and absorption reaffirm its metallic properties. The electronic band structure manifests evidence of CDW phase in the ground state. △ Less

Submitted 23 April, 2024; originally announced April 2024.

Comments: 20 pages, 6 figures

Journal ref: Adv. Theory Simul. 2024, 2400528

Ab-initio insights into the mechanical, phonon, bonding, electronic, optical and thermal properties of hexagonal W2N3 for potential applications

Authors: Istiak Ahmed, F. Parvin, R. S. Islam, S. H. Naqib

Abstract: We investigated the structural, elastic, electronic, vibrational, optical, thermodynamic and a number of thermophysical properties of W2N3 in this study using DFT based formalisms. The mechanical and dynamical stabilities have been confirmed. The Pugh and Poisson ratios are located quite close to the brittle to ductile borderline. The electronic band structure and energy density of states show met… ▽ More We investigated the structural, elastic, electronic, vibrational, optical, thermodynamic and a number of thermophysical properties of W2N3 in this study using DFT based formalisms. The mechanical and dynamical stabilities have been confirmed. The Pugh and Poisson ratios are located quite close to the brittle to ductile borderline. The electronic band structure and energy density of states show metallic behavior. The Fermi surface features are investigated. The analysis of charge density distribution map clearly shows that W atoms have comparatively high electron density around than the N atoms. Presence of covalent bondings are anticipated. High melting temperature and high phonon thermal conductivity at room temperature of W2N3 imply that the compound has potential to be used as a heat sink system. The optical characteristics demonstrate anisotropy for W2N3. The compound can be used in optoelectronic device applications due to its high absorption coefficient and low reflectivity in the visible to ultraviolet spectrum. Furthermore, the quasiharmonic Debye model is used to examine temperature and pressure dependent thermal characteristics for the first time. △ Less

Submitted 23 February, 2024; originally announced February 2024.

Comments: Submitted to Journal of Alloys and Compounds

Pressure dependent physical properties of a potential high-TC superconductor ScYH6: insights from first-principles study

Authors: Md. Ashraful Alam, F. Parvin, S. H. Naqib

Abstract: We have investigated the structural, elastic, electronic, thermophysical, superconducting, and optical properties of ScYH6 under uniform hydrostatic pressures up to 25 GPa, using the density functional theory (DFT) formalism. Most of results reported here are novel. The compound ScYH6 has been found to be elastically and thermodynamically stable within the pressure range considered. The compound i… ▽ More We have investigated the structural, elastic, electronic, thermophysical, superconducting, and optical properties of ScYH6 under uniform hydrostatic pressures up to 25 GPa, using the density functional theory (DFT) formalism. Most of results reported here are novel. The compound ScYH6 has been found to be elastically and thermodynamically stable within the pressure range considered. The compound is brittle; the brittleness decreases with increasing pressure. The elastic anisotropy is low and the machinability index is moderate which increases gradually with rising pressure. The compound is a hard material. The electronic band structure shows weakly metallic character with low density of states at the Fermi level. The Debye temperature of the compound is high and increases with increasing pressure. The Grüneisen parameter of ScYH6 is low and the phonon thermal conductivity is high at room temperature. The compound is a very efficient reflector of infrared radiation. The compound is also an efficient absorber of visible and ultraviolet light. The overall effect of pressure on optical parameters is small. We have also investigated the pressure induced changes in the predicted superconducting state properties by considering the changes in the electronic density of states at the Fermi level, Debye temperature, and the repulsive Coulomb pseudopotential. The superconducting transition temperature is found to increase gradually with increasing pressure. △ Less

Submitted 20 January, 2024; originally announced January 2024.

Comments: arXiv admin note: text overlap with arXiv:2311.06709

DFT based investigation of structural, elastic, optoelectronic, thermophysical and superconducting state properties of binary Mo3P at different pressures

Authors: Md. Sohel Rana, Razu Ahmed, Md. Sajidul Islam, R. S. Islam, S. H. Naqib

Abstract: In recent years, the investigation of novel materials for various technological applications has gained much importance in materials science research. Tri-molybdenum phosphide (Mo3P), a promising transition metal phosphide (TMP), has gathered significant attention due to its unique structural and electronic properties, which already make it potentially valuable system for catalytic and electronic… ▽ More In recent years, the investigation of novel materials for various technological applications has gained much importance in materials science research. Tri-molybdenum phosphide (Mo3P), a promising transition metal phosphide (TMP), has gathered significant attention due to its unique structural and electronic properties, which already make it potentially valuable system for catalytic and electronic device applications. Through an in-depth study using the density functional theory (DFT) calculations, this work aims to clarify the basic properties of the Mo3P compound at different pressures. In this work, we have studied the structural, elastic, optoelectronic and thermophysical properties of binary Mo3P compound. In this investigation, we varied uniform hydrostatic pressure from 0 GPa to 30 GPa. A complete geometrical optimization for structural parameters is performed and the obtained values are in good accord with the experimental values where available. It is also found that Mo3P possesses very low level of elastic anisotropy, reasonably good machinability, ductile nature, relatively high Vickers hardness, high Debye temperature and high melting temperature. Thermomechanical properties indicate that the compound has potential to be used as a thermal barrier coating material. The bonding nature in Mo3P has been explored. The electronic band structure shows that Mo3P has no band gap and exhibits conventional metallic behavior. All of the energy dependent optical characteristics demonstrate apparent metallic behavior and agree exactly with the electronic density of states calculations. The compound has excellent reflective and absorptive properties suitable for optical applications. Pressure dependent variations of the physical properties are explored and their possible link with superconductivity has been discussed. △ Less

Submitted 10 December, 2023; originally announced December 2023.

First-principles pressure dependent investigation of the physical properties of KB2H8: a prospective high-TC superconductor

Authors: Md. Ashraful Alam, F. Parvin, S. H. Naqib

Abstract: Using the density functional theory (DFT) based first-principles investigation, the structural, mechanical, hardness, elastic anisotropy, optoelectronic, and thermal properties of cubic KB2H8 have been studied within the uniform pressure range of 0 - 24 GPa. The calculated structural parameters are in good agreement with the previous theoretical work. The compound KB2H8 is found to be structurally… ▽ More Using the density functional theory (DFT) based first-principles investigation, the structural, mechanical, hardness, elastic anisotropy, optoelectronic, and thermal properties of cubic KB2H8 have been studied within the uniform pressure range of 0 - 24 GPa. The calculated structural parameters are in good agreement with the previous theoretical work. The compound KB2H8 is found to be structurally and thermodynamically stable in the pressure range from 8 GPa to 24 GPa. Single crystal elastic constants Cij and bulk elastic moduli (B, G and Y) increase systematically with pressure from 8 GPa to 24 GPa. In the stable phase, KB2H8 is moderately elastically anisotropic and ductile in nature. The compound is highly machinable and fracture resistant. The Debye temperature, melting temperature and thermal conductivity increases with pressure. The results of electronic band structure calculations and optical parameters at different pressures are consistent with each other. The compound is optically isotropic. The compound KB2H8 has potential to be used as a very efficient solar energy reflector. The electronic energy density of states at the Fermi level decreases systematically with increasing pressure. The same trend is found for the repulsive Coulomb pseudopotential. Possible relevance of the studied properties to superconductivity has also been discussed in this paper. △ Less

Submitted 11 November, 2023; originally announced November 2023.

Oxysulfide Perovskites: Reduction of the Electronic Band Gap of RbTaO3 by Sulfur Substitution to Enhance Prospective Solar Cell and Thermoelectric Performances

Authors: H. Akter, M. A. Ali, M. M. Hossain, M. M. Uddin, S. H. Naqib

Abstract: In this study, the effects of sulfur substitution on the structural, mechanical, electronic, optical, and thermodynamic properties of RbTaO3-xSx have been investigated using the WIEN2k code in the framework of density functional theory (DFT). The cubic phase of RbTaO3 transforms to tetragonal for RbTaO2S and RbTaOS2, the later transforms again to a cubic phase with added sulfur for RbTaS3. The res… ▽ More In this study, the effects of sulfur substitution on the structural, mechanical, electronic, optical, and thermodynamic properties of RbTaO3-xSx have been investigated using the WIEN2k code in the framework of density functional theory (DFT). The cubic phase of RbTaO3 transforms to tetragonal for RbTaO2S and RbTaOS2, the later transforms again to a cubic phase with added sulfur for RbTaS3. The results showed that substituting S for O anions in RbTaO3 effectively decreased the band gap from 2.717 eV to 1.438 eV, 0.286 eV, and 0.103 eV for the RbTaO3,RbTaO2S, RbTaOS2, and RbTaS3 compounds, respectively. The optical constants such as dielectric constants, refractive index, absorption coefficient, photoconductivity, reflectivity and loss function have been calculated and analyzed. The elastic constants and moduli, and their anisotropic nature were also investigated. Finally, the Debye temperature, thermal conductivity, melting temperature, specific capacities and thermal expansion coefficients were computed and analyzed using established formalisms. The reduced band gap (1.438 eV) and high absorption coefficient (~106 cm-1) of RbTaO2S makes it suitable for solar cell applications and for other visible light devices. Reduction of the band gap and phonon thermal conductivity owing to Ssubstitution is expected to enhance thermoelectric performances of the S-containing phases △ Less

Submitted 2 October, 2023; originally announced October 2023.

Comments: 41 pages

Ab-initio insights into the physical properties of XIr3 (X = La, Th) superconductors: A comparative analysis

Authors: Md. Sajidul Islam, Razu Ahmed, M. M. Hossain, M. A. Ali, M. M. Uddin, S. H. Naqib

Abstract: Here we report the structural, elastic, bonding, thermo-mechanical, optoelectronic and superconducting state properties of recently discovered XIr3 (X = La, Th) superconductors utilizing the density functional theory (DFT). The elastic, bonding, thermal and optical properties of these compounds are investigated for the first time. The calculated lattice and superconducting state parameters are in… ▽ More Here we report the structural, elastic, bonding, thermo-mechanical, optoelectronic and superconducting state properties of recently discovered XIr3 (X = La, Th) superconductors utilizing the density functional theory (DFT). The elastic, bonding, thermal and optical properties of these compounds are investigated for the first time. The calculated lattice and superconducting state parameters are in reasonable agreement to those found in the literature. In the ground state, both the compounds are mechanically stable and possess highly ductile character, high machinability, low Debye temperature, low bond hardness and significantly high melting point. The thermal conductivities of the compounds are found to be very low which suggests that they can be used for thermal insulation purpose. The population analysis and charge density distribution map confirm the presence of both ionic and covalent bonds in the compounds with ionic bond playing dominant roles. The calculated band structure and DOS profiles indicate metallic character. Unlike the significant anisotropy observed in elastic and thermal properties, all the optical constants of these compounds exhibit almost isotropic behavior. The optical constants correspond very well with the electronic band structure and DOS features. We have estimated the superconducting transition temperature of the compounds in this work. △ Less

Submitted 27 September, 2023; originally announced September 2023.

A comparative ab-initio investigation of the physical properties of cubic Laves phase compounds XBi$_2$ (X = K, Rb)

Authors: Jahid Hassan, M. A. Masum, S. H. Naqib

Abstract: In this study, we looked into a number of physical properties of alkali-bismuth compounds KBi$_2$ and RbBi$_2$ in the cubic Laves phase using the density functional theory (DFT). The structural, elastic, anisotropy indices, hardness, thermo-physical parameters, electronic band structure, and optoelectronic properties have been explored. Most of the results presented in this work are novel in natur… ▽ More In this study, we looked into a number of physical properties of alkali-bismuth compounds KBi$_2$ and RbBi$_2$ in the cubic Laves phase using the density functional theory (DFT). The structural, elastic, anisotropy indices, hardness, thermo-physical parameters, electronic band structure, and optoelectronic properties have been explored. Most of the results presented in this work are novel in nature. △ Less

Submitted 15 September, 2023; originally announced September 2023.

Comprehensive first-principles insights into the physical properties of intermetallic Zr$_3$Ir: a noncentrosymmetric superconductor

Authors: Razu Ahmed, Md. Sajidul Islam, M. M. Hossain, M. A. Ali, M. M. Uddin, S. H. Naqib

Abstract: We have looked into the structural, mechanical, optoelectronic, superconducting state and thermophysical aspects of intermetallic compound Zr$_3$Ir using the density functional theory (DFT). Many of the physical properties, including direction dependent mechanical properties, Vickers hardness, optical properties, chemical bonding nature, and charge density distributions, are being investigated for… ▽ More We have looked into the structural, mechanical, optoelectronic, superconducting state and thermophysical aspects of intermetallic compound Zr$_3$Ir using the density functional theory (DFT). Many of the physical properties, including direction dependent mechanical properties, Vickers hardness, optical properties, chemical bonding nature, and charge density distributions, are being investigated for the first time. According to this study, Zr$_3$Ir exhibits ductile features, high machinability, significant metallic bonding, a low Vickers hardness with low Debye temperature, and a modest level of elastic anisotropy. The mechanical and dynamical stabilities of Zr$_3$Ir have been confirmed. The metallic nature of Zr$_3$Ir is seen in the electronic band structures with a high electronic energy density of states at the Fermi level. The bonding nature has been explored by the charge density mapping and bond population analysis. The tetragonal Zr$_3$Ir shows a remarkable electronic stability, as confirmed by the presence of a pseudogap in the electronic energy density of states at the Fermi level between the bonding and antibonding states. Optical parameters show very good agreement with the electronic properties. The reflectivity spectra reveal that Zr$_3$Ir is a good reflector in the infrared and near-visible regions. Zr$_3$Ir is an excellent ultra-violet (UV) radiation absorber. High refractive index at visible photon energies indicates that Zr$_3$Ir could be used to improve the visual aspects of electronic displays. All the optical constants exhibit a moderate degree of anisotropy. Zr$_3$Ir has a moderate melting point, high damage tolerance, and very low minimum thermal conductivity. The thermomechanical characteristics of Zr$_3$Ir reveal that it is a potential thermal barrier coating material. The superconducting state parameters of Zr$_3$Ir are also explored. △ Less

Submitted 11 July, 2023; originally announced July 2023.

DFT insights into MAX phase borides Hf2AB [A = S, Se, Te] in comparison with MAX phase carbides Hf2AC [A = S, Se, Te]

Authors: J. Islam, M. D. Islam, M. A. Ali, H. Akter, A. Hossain, M. Biswas, M. M. Hossain, M. M. Uddin, S. H. Naqib

Abstract: In this work, density functional theory (DFT) based calculations were performed to compute the physical properties (structural stability, mechanical behavior, electronic, thermodynamic, and optical properties) of synthesized MAX phases Hf2SB, Hf2SC, Hf2SeB, Hf2SeC, Hf2TeB, and the as-yet-undiscovered MAX carbide phase Hf2TeC. Calculations of formation energy, phonon dispersion curves, and elastic… ▽ More In this work, density functional theory (DFT) based calculations were performed to compute the physical properties (structural stability, mechanical behavior, electronic, thermodynamic, and optical properties) of synthesized MAX phases Hf2SB, Hf2SC, Hf2SeB, Hf2SeC, Hf2TeB, and the as-yet-undiscovered MAX carbide phase Hf2TeC. Calculations of formation energy, phonon dispersion curves, and elastic constants confirmed the stability of the aforementioned compounds. The obtained values of lattice parameters, elastic constants, and elastic moduli of Hf2SB, Hf2SC, Hf2SeB, Hf2SeC, and Hf2TeB showed fair agreement with earlier studies, whereas the values of the mentioned parameters for the predicted Hf2TeC exhibit a good consequence of B replacement by C. The anisotropic mechanical properties are exhibited by the considered MAX phases. The metallic nature and its anisotropic behavior were revealed by the electronic band structure and density of states. The analysis of the thermal properties Debye temperature, melting temperature, minimum thermal conductivity, and Gruneisen parameter confirmed that the carbide phases were more suited than the boride phases considered herein. The MAX phase response to incoming photons further demonstrated that they were metallic. Their suitability for use as coating materials to prevent solar heating was demonstrated by the reflectivity spectra. Additionally, this study demonstrated the impact of B replacing C in the MAX phases. △ Less

Submitted 21 June, 2023; originally announced June 2023.

Comments: 38 pages

Ab-initio insights into the structural, elastic, bonding, and thermophysical properties of UHx (x = 1, 2, 3, 5, 6, 7, 8) under pressure: possible relevance to high-Tc superconductivity

Authors: Md. Ashraful Alam, F. Parvin, S. H. Naqib

Abstract: Binary uranium hydrides, UHx (x = 1, 2, 3, 5, 6, 7, 8), with different crystal symmetries are potentially interesting compounds for high-Tc superconductivity and as hydrogen storage systems. In this work we have explored the structural, elastic, mechanical, bonding, and thermophysical properties of these systems under uniform pressure via density functional theory based computations. Most of the r… ▽ More Binary uranium hydrides, UHx (x = 1, 2, 3, 5, 6, 7, 8), with different crystal symmetries are potentially interesting compounds for high-Tc superconductivity and as hydrogen storage systems. In this work we have explored the structural, elastic, mechanical, bonding, and thermophysical properties of these systems under uniform pressure via density functional theory based computations. Most of the results disclosed in this work are novel. From the calculations of the cohesive energy and enthalpy of formation, we have found that the titled compounds are chemically stable. The computed elastic constants at different pressures ensure elastic stability. All the binary hydrides are mechanically anisotropic. Pressure induced brittle-ductile transition takes place under high pressure. The compounds are machinable with the cubic α-UH3-Pm-3n showing very high value of the machinability index. All the compounds are fairly hard with cubic UH8 showing superhard character. The Debye temperatures and acoustic velocities of these compounds are high; the highest value is found for the cubic UH8. The melting temperature, Grüneisen parameter, minimal phonon thermal conductivity, and the thermal expansion coefficient of these compounds have also been studied at different pressures. All these parameters show excellent correspondence with the estimated Debye temperature, elastic parameters and bonding characteristics. △ Less

Submitted 4 June, 2023; originally announced June 2023.

Comments: arXiv admin note: text overlap with arXiv:2211.09457

Structural, elastic, electronic, bonding, thermo-mechanical and optical properties of predicted NbAlB MAB phase in comparison to MoAlB: DFT based ab-initio insights

Authors: Mst. Bina Aktar, F. Parvin, A. K. M. Azharul Islam, S. H. Naqib

Abstract: In this study, we have used density functional theory (DFT) based first-principles investigation of the physical properties of prospective NbAlB compound for the first time. From the analysis of the cohesive energy and enthalpy of formation, it was found that NbAlB is chemically stable. The physical properties of NbAlB have been compared and contrasted with those obtained for MoAlB. Both these MAB… ▽ More In this study, we have used density functional theory (DFT) based first-principles investigation of the physical properties of prospective NbAlB compound for the first time. From the analysis of the cohesive energy and enthalpy of formation, it was found that NbAlB is chemically stable. The physical properties of NbAlB have been compared and contrasted with those obtained for MoAlB. Both these MAB phases are elastically anisotropic, mechanically stable, machinable and brittle materials. Structural and elastic features reflect the layered features. The estimated hardness of NbAlB is 19.0 GPa comparable to that of MoAlB (20.8 GPa) suggesting that predicted NbAlB is a hard compound and is suitable for heavy duty industrial applications. NbAlB is more machinable than MoAlB. Electronic band structure calculations reveal conventional metallic behavior with the electronic density of states at the Fermi level arising mainly due to the Nb 4d orbitals in NbAlB. The electronic density of states at the Fermi level is significantly higher in NbAlB in comparison to MoAlB, indicating that NbAlB is expected to exhibit higher level of electrical conductivity. Electronic dispersion is highly anisotropic for both MoAlB and NbAlB with substantially large electronic effective masses in the out-of-plane directions. The bonding features have been elucidated via the analysis of the band structure and charge density distribution. Both the compounds have mixed covalent, ionic and metallic bonding characteristics. The Fermi surfaces of MoAlB and NbAlB consists of electron and hole like sheets. The Debye temperatures of MoAlB and NbAlB are comparable. The estimated melting temperature of NbAlB is somewhat lower than that of MoAlB. NbAlB shows excellent reflection characteristics suitable to be used as an efficient solar reflector. NbAlB is also expected to absorb ultraviolet radiation very effectively. △ Less

Submitted 21 May, 2023; originally announced May 2023.

Ab-initio investigation of the physical properties of BaAgAs Dirac semimetal and its possible thermo-mechanical and optoelectronic applications

Authors: A. S. M. Muhasin Reza, S. H. Naqib

Abstract: BaAgAs is a ternary Dirac semimetal which can be tuned across a number of topological orders. In this study we have investigated the bulk physical properties of BaAgAs using density functional theory based computations. Most of the results presented in this work are novel. The optimized structural parameters are in good agreement with previous results. The elastic constants indicate that BaAgAs is… ▽ More BaAgAs is a ternary Dirac semimetal which can be tuned across a number of topological orders. In this study we have investigated the bulk physical properties of BaAgAs using density functional theory based computations. Most of the results presented in this work are novel. The optimized structural parameters are in good agreement with previous results. The elastic constants indicate that BaAgAs is mechanically stable and brittle in nature. The compound is moderately hard and possesses fair degree of machinability. There is significant mechanical/elastic anisotropy in BaAgAs. The Debye temperature of the compound is medium and the phonon thermal conductivity and melting temperature are moderate as well. The bonding character is mixed with notable covalent contribution. The electronic band structure calculations reveal clear semimetallic behavior with a Dirac node at the Fermi level. BaAgAs has a small ellipsoidal Fermi surface centered at the G-point of the Brillouin zone. The phonon dispersion curves show dynamical stability. There is a clear phonon band gap between the acoustic and the optical branches. The energy dependent optical constants conform to the band structure calculations. The compound is an efficient absorber of the ultraviolet light and has potential to be used as an anti-reflection coating. Optical anisotropy of BaAgAs is moderate. The computed repulsive Coulomb pseudopotential is low indicating that the electronic correlations in this compound are not strong. △ Less

Submitted 12 May, 2023; originally announced May 2023.

Comments: Submitted for publication. arXiv admin note: text overlap with arXiv:2303.01319

A comprehensive ab-initio insights into the pressure dependent mechanical, phonon, bonding, electronic, optical, and thermal properties of CsV3Sb5 Kagome compound

Authors: M. I. Naher, M. A. Ali, M. M. Hossain, M. M. Uddin, S. H. Naqib

Abstract: In this paper, we have presented a comprehensive study of the physical properties of Kagome superconductor CsV3Sb5 using the density functional theory (DFT). The structural, mechanical, electronic, atomic bonding, hardness, thermodynamic, and optical properties, and their pressure dependences have been investigated for the first time. The calculated ground state lattice parameters and volume are i… ▽ More In this paper, we have presented a comprehensive study of the physical properties of Kagome superconductor CsV3Sb5 using the density functional theory (DFT). The structural, mechanical, electronic, atomic bonding, hardness, thermodynamic, and optical properties, and their pressure dependences have been investigated for the first time. The calculated ground state lattice parameters and volume are in excellent agreement with available experimental results. The estimated single-crystal elastic constants ensured the mechanical stability of the compound, whereas phonon spectra endorse dynamical stability at zero pressure. The electronic band structure, energy density of states, optical properties confirmed the metallic features. The Pugh ratio, Poisson's ratio of the compound revealed softness and ductility. The hardness, estimated from several formulae, is quite low while the machinability index predicted good machinability with excellent dry lubricating properties. The compound shows tendency towards structural instability at a pressure around 18 GPa. The optical constants have also been studied to correlate those with electronic properties and to predict possible applications of this compound. Both mechanical and optical properties show anisotropy.CsV3Sb5 is predicted to be an efficient absorber of ultraviolet radiation. The compound is also an efficient reflector of visible light. △ Less

Submitted 15 April, 2023; originally announced April 2023.

DFT based investigation of bulk mechanical, thermophysical and optoelectronic properties of PbTaSe2 topological semimetal

Authors: A. S. M. Muhasin Reza, S. H. Naqib

Abstract: PbTaSe2 is a non-centrosymmetric topological semimetal. In this work we have explored the structural, elastic, mechanical, bonding, electronic, acoustic, thermal, and optical properties of PbTaSe2. The electronic bond structure calculations confirm semi-metallic character. Fermi surface topology shows both electron and hole sheets. The single crystal elastic constants reveal that PbTaSe2 is elasti… ▽ More PbTaSe2 is a non-centrosymmetric topological semimetal. In this work we have explored the structural, elastic, mechanical, bonding, electronic, acoustic, thermal, and optical properties of PbTaSe2. The electronic bond structure calculations confirm semi-metallic character. Fermi surface topology shows both electron and hole sheets. The single crystal elastic constants reveal that PbTaSe2 is elastically stable. The compound is soft, brittle, and highly machinable at the same time. It also possesses very high level of dry lubricity. Various anisotropy indicators suggest that PbTaSe2 is elastically anisotropic with layered character. The phonon dynamics has been investigated. Phonon dispersion plot shows that the compound is dynamically stable with a clear frequency gap between the acoustic and optical branches. The Debye temperature, phonon thermal conductivity, and melting temperature of PbTaSe2 is low. The compound has medium Grüneisen parameter. The bonding character is mainly dominated by ionic bonding with some metallic contribution. The optical parameters have been studied in detail. The optical spectra reveal metallic features. The compound reflects visible light very efficiently (reflectance above 60%). It is also an efficient absorber of the ultraviolet light. The compound exhibits significant optical anisotropy with respect to the polarization directions of the incident electric field. △ Less

Submitted 2 March, 2023; originally announced March 2023.

Interrelations among critical current density, irreversibility field and pseudogap in hole doped high-Tc cuprates

Authors: S. H. Naqib, R. S. Islam

Abstract: The effects of hole content (p) and oxygen deficiency (delta) on the zero-field critical current density, Jc0, were investigated for high-quality c-axis oriented Y1-xCaxBa2Cu3O7-delta (x = 0, 0.05, 0.10, and 0.20) thin films. Low temperature critical current density of these films above the optimum doping were found to be high and were primarily determined by the hole concentration, reaching a max… ▽ More The effects of hole content (p) and oxygen deficiency (delta) on the zero-field critical current density, Jc0, were investigated for high-quality c-axis oriented Y1-xCaxBa2Cu3O7-delta (x = 0, 0.05, 0.10, and 0.20) thin films. Low temperature critical current density of these films above the optimum doping were found to be high and were primarily determined by the hole concentration, reaching a maximum at p ~ 0.185 +/- 0.005, irrespective of the level of oxygen deficiency. This implies that oxygen disorder plays only a secondary role and the intrinsic Jc0 is primarily governed by the carrier concentration in the copper oxide planes. Further support in favor of this was found from the analysis of the in-plane resistive transitions of c-axis oriented crystalline thin films of YBa2Cu3O7-delta (YBCO) under magnetic fields (H) applied along the c-direction, over a wide range of doped holes. The characteristic magnetic field (H0), linked to the vortex activation energy and the irreversibility field, exhibits similar p-dependence as shown by Jc0(p). We have explained these observations in terms of the doping dependent pseudogap (PG) in the low-energy electronic energy density of states. Both the intrinsic critical current density and the irreversibility field depend directly on the superconducting condensation energy, which in turn is largely controlled by the magnitude of the hole concentration dependent PG in the quasiparticle spectral density. △ Less

Submitted 26 December, 2022; originally announced December 2022.

Comments: Submitted to Superconductivity

Ab-initio insights into the pressure dependent physical properties and possible high-Tc superconductivity in monoclinic and orthorhombic MgVH6

Authors: Md. Ashraful Alam, F. Parvin, S. H. Naqib

Abstract: Here we have used the density functional theory (DFT) with the GGA-PBE approximation to investigate the structural, mechanical, electronic, hardness, thermal, superconductivity and optoelectronic properties under pressure for monoclinic (P21/m) and orthorhombic (Pmn21) structures of MgVH6. We have studied optical properties of P21/m phase at 0 GPa and Pmn21 phase at 100 GPa only (considering phase… ▽ More Here we have used the density functional theory (DFT) with the GGA-PBE approximation to investigate the structural, mechanical, electronic, hardness, thermal, superconductivity and optoelectronic properties under pressure for monoclinic (P21/m) and orthorhombic (Pmn21) structures of MgVH6. We have studied optical properties of P21/m phase at 0 GPa and Pmn21 phase at 100 GPa only (considering phase stability). Both of the phases of MgVH6 are thermodynamically stable. P21/m phase is mechanically stable but Pmn21 is mechanically unstable in our calculations for the pressures considered. Monoclinic (P21/m) is ductile in nature, on the other hand, orthorhombic (Pmn21) is brittle in nature at 100 GPa and becomes ductile for pressures in the range from 125 GPa to 200 GPa. Hardness calculations indicate superhard character of orthorhombic (Pmn21) structure at 100 GPa. The melting temperature of orthorhombic crystal is very high. This also agrees with the bulk modulus, Debye temperature, and hardness calculations. We have calculated theoretically the superconducting transition temperature Tc at different pressures only for the orthorhombic (Pmn21) structure following a previous study. The estimated values of transition temperatures are within 104.7 K to 26.1 K in the pressure range from 100 GPa to 200 GPa. MgVH6, in both the structures, are elastically and optically anisotropic. △ Less

Submitted 17 November, 2022; originally announced November 2022.

A comparative study of the structural, elastic, thermophysical, and optoelectronic properties of CaZn$_2$X$_2$ (X = N, P, As) semiconductors via ab-initio approach

Authors: Md. Sajidul Islam, Razu Ahmed, Md. Mahamudujjaman, R. S. Islam, S. H. Naqib

Abstract: We present a detailed density functional theory based calculations of the structural, elastic, lattice dynamical, thermophysical, and optoelectronic properties of ternary semiconductors CaZn$_2$X$_2$ (X = N, P, As) in this paper. The obtained lattice parameters are in excellent agreement with the experimental values and other theoretical findings. These elastic constants satisfy the mechanical sta… ▽ More We present a detailed density functional theory based calculations of the structural, elastic, lattice dynamical, thermophysical, and optoelectronic properties of ternary semiconductors CaZn$_2$X$_2$ (X = N, P, As) in this paper. The obtained lattice parameters are in excellent agreement with the experimental values and other theoretical findings. These elastic constants satisfy the mechanical stability criteria. Moreover, many thermophysical parameters of these compounds are estimated, including the Debye temperature, average sound velocity, melting temperature, heat capacity, lattice thermal conductivity, etc. The comprehensive analysis of the elastic constants and moduli show that CaZn$_2$X$_2$ compounds possess reasonably good machinability, relatively high Vickers hardness and relatively low Debye temperature. The phonon dispersion curves and phonon density of states are investigated for the first time for the compounds CaZn$_2$P$_2$ and CaZn$_2$As$_2$. It is observed from the phonon dispersion curves that the bulk CaZn$_2$X$_2$ (X = N, P, As) compounds are dynamically stable. Electronic properties have been studied through the band structures and electronic energy density of states. The electronic band structures show that CaZn$_2$N$_2$ and CaZn$_2$As$_2$ possess direct band gaps while the compound CaZn$_2$P$_2$ show indirect band gap. The bonding characters of CaZn$_2$X$_2$ (X = N, P, As) compounds are investigated. Energy dependent optical parameters exhibit good correspondence with the electronic energy density of states features. We have thoroughly discussed the reflectivity, absorption coefficient, refractive index, dielectric function, optical conductivity and loss function of these semiconductors. The optical absorption, reflectivity spectra and the refractive index of CaZn$_2$X$_2$ (X = N, P, As) show that the compounds hold promise to be used in optoelectronic devices. △ Less

Submitted 31 October, 2022; originally announced October 2022.

Pressure-dependent semiconductor-metal transition and elastic, electronic, optical, and thermophysical properties of SnS binary chalcogenide

Authors: Ayesha Tasnim, Md. Mahamudujjaman, Md. Asif Afzal, R. S. Islam, S. H. Naqib

Abstract: Density functional theory based study of the pressure dependent physical properties of binary SnS compound has been carried out. The computed elastic constants reveal that SnS is mechanically stable and brittle under ambient conditions. With increasing pressure, the compound becomes ductile. The Poisson's ratio also indicates brittle-ductile transition with increasing pressure. The hardness of SnS… ▽ More Density functional theory based study of the pressure dependent physical properties of binary SnS compound has been carried out. The computed elastic constants reveal that SnS is mechanically stable and brittle under ambient conditions. With increasing pressure, the compound becomes ductile. The Poisson's ratio also indicates brittle-ductile transition with increasing pressure. The hardness of SnS increases significantly with pressure. The compound possesses elastic anisotropy. The ground state electronic band structure is semiconducting with a small band gap which becomes metallic under pressure. The band becomes more and more dispersive with the increase in pressure while the electronic correlations decrease as pressure is raised. Both the Debye temperature and the phonon thermal conductivity of SnS increase sharply with pressure. The Melting temperature of the compound is low. Mixed bonding characteristics are found with ionic and covalent contributions. SnS is a good absorber of ultraviolet light. The reflectivity of the material increases with the increase in pressure. The reflectivity is nonselective over a wide spectral range. The low energy refractive index is high. All these optical characteristics are useful for prospective optoelectronic device applications. The optical anisotropy is low. △ Less

Submitted 28 October, 2022; originally announced October 2022.

Comparative analysis of physical properties of some binary transition metal carbides XC (X = Nb, Ta, Ti): Insights from a comprehensive ab-initio study

Authors: Razu Ahmed, Md. Mahamudujjaman, Md. Asif Afzal, Md. Sajidul Islam, R. S. Islam, S. H. Naqib

Abstract: Binary metallic carbides belong to a technologically prominent class of materials. We have explored the structural, mechanical, electronic, optical, and some thermophysical properties of XC (X = Nb, Ta, Ti) binary metallic carbides in details employing first-principles method. Some of the results obtained are novel. A comparative analysis has been made. Binary metallic carbides belong to a technologically prominent class of materials. We have explored the structural, mechanical, electronic, optical, and some thermophysical properties of XC (X = Nb, Ta, Ti) binary metallic carbides in details employing first-principles method. Some of the results obtained are novel. A comparative analysis has been made. △ Less

Submitted 23 September, 2022; originally announced September 2022.

A comparative study of the physical properties of layered transition metal nitride halides MNCl (M = Zr, Hf): DFT based insights

Authors: Shaher Azad, B. Rahman Rano, Ishtiaque M. Syed, S. H. Naqib

Abstract: ZrNCl and HfNCl belong to a class of layered transition metal nitride halides MNCl (M= Zr,H). They are from the space group R-3m (No-166) and crystallize in the rhombohedral structure. Both of these materials have shown promising semiconducting behaviors. Recent studies have shown their versatility as semiconductors and also as superconductors when intercalated with alkaline metals. This paper exp… ▽ More ZrNCl and HfNCl belong to a class of layered transition metal nitride halides MNCl (M= Zr,H). They are from the space group R-3m (No-166) and crystallize in the rhombohedral structure. Both of these materials have shown promising semiconducting behaviors. Recent studies have shown their versatility as semiconductors and also as superconductors when intercalated with alkaline metals. This paper explores the mechanical, optical and electronic properties of these two semiconducting crystals in depth. A comparative study between the two materials in their elastic constants, anisotropy measures, electronic density of states and band structures, optical spectra has been performed with first principles density functional theory (DFT) based calculations within the local density approximation (with appropriate U for the energy gap calculations in case of HfNCl). HfNCl is more machinable than ZrNCl and is relatively softer as indicated by the lower Debye temperature. ZrNCl has stronger layering due to which it exhibits brittle nature. HfNCl has a larger band gap. ZrNCl is a better reflector of ultraviolet radiation. On the other hand HfNCl is a good ultraviolet absorber. Both materials are anisotropic in regards to structure, electronic energy dispersion and optical parameters. Overall, the degree of anisotropy is more prominent in ZrNCl compared to that in HfNCl. Possible sectors for applications of ZrNCl and HfNCl semiconductors are discussed. △ Less

Submitted 11 September, 2022; originally announced September 2022.

The rise of 212 MAX phase borides, Ti$_2$PB$_2$, Zr$_2$PbB$_2$, and Nb$_2$AB$_2$ [A = P, S]: DFT insights into the physical properties for thermo-mechanical applications

Authors: M. A. Ali, M. M. Hossain, M. M. Uddin, A. K. M. A. Islam, S. H. Naqib

Abstract: An interesting class of ternary metallic borides, known as the 212 MAX phase borides, is the recent advancement of the MAX phase family. In this article, results from ab-initio calculations on unexplored Ti$_2$PB$_2$, Zr$_2$PbB$_2$, and Nb$_2$AB$_2$ [A = P, S] are reported wherein Ti$_2$PB$_2$ along with its 211 boride phase Ti$_2$PB are predicted for the first time. The stability was confirmed by… ▽ More An interesting class of ternary metallic borides, known as the 212 MAX phase borides, is the recent advancement of the MAX phase family. In this article, results from ab-initio calculations on unexplored Ti$_2$PB$_2$, Zr$_2$PbB$_2$, and Nb$_2$AB$_2$ [A = P, S] are reported wherein Ti$_2$PB$_2$ along with its 211 boride phase Ti$_2$PB are predicted for the first time. The stability was confirmed by calculating the formation energy, phonon dispersion curve, and elastic stiffness constants. The obtained elastic constants, elastic moduli, and Vickers hardness values of Ti$_2$PB$_2$, Zr$_2$PbB$_2$, and Nb$_2$AB$_2$ [A = P, S] were found to be significantly larger than those of their counterparts 211 borides and carbides, in a trend similar to other 212 borides. The studied compounds are brittle like most of the MAX and MAB phases. The electronic band structure and density of states revealed the metallic nature of the titled borides. Several thermal parameters were explored, certifying the suitability of Ti2PB2, Zr2PbB2, and Nb2AB2 [A = P, S] compared to their counterparts, and a similar trend was found for the other 212 borides. The obtained results predict that Ti2PB2, Zr2PbB2, and Nb2AB2 [A = P, S] have significant potential for use as efficient thermal barrier coating materials. The response of Ti$_2$PB$_2$, Zr$_2$PbB$_2$, and Nb$_2$AB$_2$ [A = P, S] to the incident photon was studied by computing the dielectric constant (real and imaginary part), refractive index, absorption coefficient, photoconductivity, reflectivity, and energy loss function. The ability to protect from solar heating was revealed from the studied reflectivity spectra. In this work, we have explored the physical basis of the improved thermo-mechanical properties of 212 MAX phase borides compared to their carbide and boride counterparts. △ Less

Submitted 2 September, 2022; v1 submitted 17 July, 2022; originally announced July 2022.

Comments: 36 pages

An ab initio approach to understand the structural, thermophysical, electronic, and optical properties of binary silicide SrSi2: A double Weyl semimetal

Authors: Suptajoy Barua, B. Rahman Rano, Ishtiaque M. Syed, S. H. Naqib

Abstract: A large number of hitherto unexplored elastic, thermophysical, acoustic, and optoelectronic properties of a double Weyl semimetal SrSi2 have been investigated in this study. Density functional theory (DFT) based methodology has been employed. Analyses of computed elastic parameters reveal that SrSi2 is a mechanically stable, ductile, moderately machinable, and relatively soft material. The compoun… ▽ More A large number of hitherto unexplored elastic, thermophysical, acoustic, and optoelectronic properties of a double Weyl semimetal SrSi2 have been investigated in this study. Density functional theory (DFT) based methodology has been employed. Analyses of computed elastic parameters reveal that SrSi2 is a mechanically stable, ductile, moderately machinable, and relatively soft material. The compound is predicted to be dynamically stable and possesses significant metallic bonding. Study of thermophysical properties, namely, Debye temperature, Grüneisen parameter, acoustic parameters, melting temperature, heat capacity, thermal expansion coefficient, and dominant phonon mode is also indicative of soft nature of SrSi2. The electronic band structure calculations without and with spin-orbit coupling disclose semimetallic character with clear Weyl nodes close to the Fermi level. The electronic dispersion is anisotropic characterized by nearly flat and linear regions within the Brillouin zone. Optical parameters at different photon energies are investigated. SrSi2 shows excellent nonselective reflection spectrum across an extended range of energy encompassing the visible region implying that the compound under study has significant potential to be used as an efficient solar energy reflector. SrSi2 absorbs ultraviolet light quite efficiently. The compound also possesses high refractive index in the low energy. All these optical features can be useful in optoelectronic device applications. △ Less

Submitted 24 April, 2022; originally announced April 2022.

Possible applications of Mo2C in the orthorhombic and hexagonal phases explored via ab-initio investigations of elastic, bonding, optoelectronic and thermophysical properties

Authors: M. I. Naher, S. H. Naqib

Abstract: Binary carbides demonstrate attractive set of physical properties that are suitable for numerous and diverse applications. In the present study, we have explored the structural properties, electronic structures, elastic constants, acoustic behaviors, phonon dispersions, optical properties, and various thermophysical properties of binary orthogonal and hexagonal Mo2C compounds in details via first-… ▽ More Binary carbides demonstrate attractive set of physical properties that are suitable for numerous and diverse applications. In the present study, we have explored the structural properties, electronic structures, elastic constants, acoustic behaviors, phonon dispersions, optical properties, and various thermophysical properties of binary orthogonal and hexagonal Mo2C compounds in details via first-principles calculations using the density functional theory (DFT). The calculated ground state lattice parameters in both the symmetries are in excellent agreement with available experimental results. The calculated electronic band structure, density of states, and optical properties of Mo2C in both structures reveal metallic features. The orthorhombic crystal shows higher level mechanical and thermal anisotropy compared to that in the hexagonal phase. The elastic constants and phonon dispersion calculations show that, in both structures, Mo2C is mechanically and dynamically stable. A comprehensive mechanical and thermophysical study shows that both phases possess high structural stability, reasonably good machinability, ductile nature, high hardness, low compressibility, high Debye temperature and high melting temperature. Moreover, the electronic energy density of states, electron density distribution, elastic properties, and Mulliken bond population analyses indicate that the structures under consideration consist of mixed bonding characteristics with ionic and covalent contributions. High reflectivity over wide spectral range makes the compound suitable as reflecting coating. Both the structures are efficient absorber of ultraviolet radiation. The refractive indices are quite high in the infrared to visible range. △ Less

Submitted 29 January, 2022; originally announced January 2022.

First-principles insights into the mechanical, optoelectronic, thermophysical, and lattice dynamical properties of binary topological semimetal BaGa2

Authors: M. I. Naher, S. H. Naqib

Abstract: In the present study we have investigated the structural properties, electronic band dispersion, elastic constants, acoustic behavior, phonon spectrum, optical properties, and a number of thermophysical parameters of binary topological semimetal BaGa2 in details via first-principles calculations using the density functional theory (DFT) based formalisms. The electronic band structure and density o… ▽ More In the present study we have investigated the structural properties, electronic band dispersion, elastic constants, acoustic behavior, phonon spectrum, optical properties, and a number of thermophysical parameters of binary topological semimetal BaGa2 in details via first-principles calculations using the density functional theory (DFT) based formalisms. The electronic band structure and density of states calculations with spin orbit coupling reveal semimetallic nature with clear topological signature. The minimum thermal conductivities and anisotropies of the compound are calculated. The elastic constants, phonon dispersion calculations show that the compound under study is both mechanically and dynamically stable. Comprehensive study of elastic constants and moduli shows that BaGa2 possesses fairly isotropic mechanical properties, reasonably good machinability, low Debye temperature and melting point. The chemical bonding in BaG2 is interpreted via the electronic energy density of states, electron density distribution, elastic properties and Mulliken bond population analysis. The compound possesses both ionic and covalent bondings. The reflectivity spectra show strong anisotropy with respect to polarization of the incident electric field in the visible to mid-ultraviolet regions. High reflectivity over wide spectral range makes BaGa2 suitable as a reflecting material. BaGa2 is also an efficient absorber of ultraviolet radiation. Furthermore, the refractive index is quite high in the infrared to visible range. All the energy dependent optical parameters show metallic features and are in complete accord with the underlying bulk electronic density of states calculations. Most of the results presented in this study are novel and should serve as useful reference for future study. △ Less

Submitted 1 January, 2022; originally announced January 2022.

First-principles prediction of pressure dependent mechanical, electronic, optical, and superconducting state properties of NaC6: A potential high-Tc superconductor

Authors: Nazmun Sadat Khan, B. Rahman Rano, Ishtiaque M. Syed, R. S. Islam, S. H. Naqib

Abstract: Very recently carbon-rich NaC6 with sodalite-like structure has been predicted to show superconducting transition temperature above 100 K at relatively low applied (compared to high-Tc hydrides) hydrostatic pressures. We have investigated the pressure dependent structural, elastic, electronic, superconducting state, and optoelectronic properties of NaC6 in this study. Some important thermophysical… ▽ More Very recently carbon-rich NaC6 with sodalite-like structure has been predicted to show superconducting transition temperature above 100 K at relatively low applied (compared to high-Tc hydrides) hydrostatic pressures. We have investigated the pressure dependent structural, elastic, electronic, superconducting state, and optoelectronic properties of NaC6 in this study. Some important thermophysical properties have also been explored. The elastic properties along with Poisson's and Pugh's ratios and optoelectronic parameters are investigated for the first time. NaC6 was found to be structurally stable only at high pressures at and above 40 GPa, in agreement with previous study. The compound is highly ductile and the chemical bonding is predominantly metallic in nature. The Debye temperature shows strong pressure dependence. The Gruneisen parameter also exhibits significant pressure dependence. The electronic band structure reveals metallic character and consists of highly dispersive and almost flat bands crossing the Fermi level. Both the electronic density of states at the Fermi level and repulsive Coulomb pseudopotential increase gradually with increasing pressure in the range 40 GPa to 70 Gpa. The degree of dispersion in the E(k) curves depend weakly on pressure both in the valence and conduction bands. The optical parameters spectra, studied for the first time, correspond well with the electronic band structure. NaC6 absorbs and reflects electromagnetic radiation quite efficiently in the mid-ultraviolet region. Superconducting transition temperatures of NaC6 have been estimated at different pressures and compared with previously reported values. The effects of various parameters on Tc have been discussed in details. △ Less

Submitted 7 September, 2021; originally announced September 2021.

Comments: Submitted for publication

Newly synthesized 3D boron-rich chalcogenides B12X (X = S, Se): Theoretical characterization of physical properties for optoelectronic and mechanical applications

Authors: M. M. Hossain, M. A. Ali, M. M. Uddin, S. H. Naqib, A. K. M. A. Islam

Abstract: Boron rich chalcogenides have been predicted to have excellent properties for optical and mechanical applications in recent times. In this regard, we report the electronic, optical and mechanical properties of recently synthesized boron rich chalcogenide compounds, B12X (X = S and Se) using density functional theory for the first time. The effects of exchange and correlation functional on these pr… ▽ More Boron rich chalcogenides have been predicted to have excellent properties for optical and mechanical applications in recent times. In this regard, we report the electronic, optical and mechanical properties of recently synthesized boron rich chalcogenide compounds, B12X (X = S and Se) using density functional theory for the first time. The effects of exchange and correlation functional on these properties are also investigated. The consistency of the obtained crystal structure with the reported experimental results has been checked in terms of lattice parameters. The considered materials are mechanically stable, brittle and elastically anisotropic. Furthermore, the elastic moduli and hardness parameters are calculated, which show that B12S is likely to be a prominent member of hard materials family compared to B12Se. The origin of different in hardness is explained on the basis of density of states near the Fermi level. Reasonably good values of fracture toughness and machinability index for B12X (X= S and Se) are reported. The melting point, Tm for the B12S and B12Se compounds suggests that both solids are stable, at least up to 4208 and 3577 K, respectively. Indirect band gap of B12S (2.27 eV) and B12Se (1.30 eV) are obtained using the HSE06 functional.The electrons of B12Se compound show lighter average effective mass compared to that of B12S compound, which signifies higher mobility of charge carriers in B12Se. The optical properties are characterized using GGA-PBE and HSE06 method and discussed in detail. These compounds possess bulk optical anisotropy and excellent absorption coefficients in visible light region along with very low static value of reflectivity spectra (range: 7.42-14.0% using both functionals) are noted. Such useful features of the compounds under investigation show promise for applications in optoelectronic and mechanical sectors. △ Less

Submitted 19 August, 2021; originally announced August 2021.

Comments: 34 pages, 13 figures, 6 Tables, This study will be submitted for publication internationally very soon

Ab-initio insights into the elastic, bonding, phonon, optoelectronic and thermophysical properties of SnTaS2

Authors: M. I. Naher, M. Mahamudujjaman, A. Tasnim, R. S. Islam, S. H. Naqib

Abstract: SnTaS2 is a recently discovered layered semimetal exhibiting type-II low transition temperature superconductivity. Except some superconductivity related parameters, most of the physical properties, namely, elastic, mechanical, bonding, phonon dispersion, acoustic, thermophysical, and optical properties of SnTaS2 are unexplored till now. In this study, we have investigated these hitherto unexplored… ▽ More SnTaS2 is a recently discovered layered semimetal exhibiting type-II low transition temperature superconductivity. Except some superconductivity related parameters, most of the physical properties, namely, elastic, mechanical, bonding, phonon dispersion, acoustic, thermophysical, and optical properties of SnTaS2 are unexplored till now. In this study, we have investigated these hitherto unexplored properties of SnTaS2 for the first time employing density functional theory (DFT) based first-principles method. SnTaS2 is a mechanically stable, elastically anisotropic compound with strongly layered feature. The bond hardness and Vickers hardness have been calculated. The material under study is ductile, soft and highly machinable. The chemical bonding feature has mixed character with significant contribution coming from the ionic channel. Phonon dispersion curves disclose dynamical stability. Electronic band structure calculations show simple metallic character. The Fermi surface consists of both electron-like and hole-like sheets with varying degrees of dispersion. The low energy (including visible part of the spectrum) refractive index of SnTaS2 is high. The reflectivity is fairly nonselective over a wide range of photon energy and the absorption coefficient is large in the mid ultraviolet region. The Debye temperature and thermal conductivity of SnTaS2 are low. The electron-phonon coupling constant has been calculated. The compound under study possesses optical anisotropy with respect to the polarization direction of the incident electric field. △ Less

Submitted 16 August, 2021; originally announced August 2021.

Magnetic Field and Frequency Dependent AC Susceptibility of High-Tc YBCO Single Crystal

Authors: M. Rakibul Hasan Sarkar, S. H. Naqib

Abstract: The temperature dependence of AC susceptibility (ACS) has been measured for a very high-quality plate-like slightly overdoped YBCO single crystal for different frequencies and AC magnetic field amplitudes. Frequency dependence of the ACS is weak irrespective of the magnetic field orientation but significant effects of field orientation with respect to the CuO2 planes and field magnitude on real an… ▽ More The temperature dependence of AC susceptibility (ACS) has been measured for a very high-quality plate-like slightly overdoped YBCO single crystal for different frequencies and AC magnetic field amplitudes. Frequency dependence of the ACS is weak irrespective of the magnetic field orientation but significant effects of field orientation with respect to the CuO2 planes and field magnitude on real and imaginary components of fundamental ACS were observed. The height of the loss peak saturates as full penetration of magnetic field is achieved. The peak temperature, Tp, in \c{hi}" shifts to lower temperatures with increasing magnetic field amplitude for both HIIc and HIIab. The value of Tp depends on the orientation of the magnetic field with respect to the crystallographic axes, illustrating the anisotropy in the magnetic flux dynamics. The superconducting transition width increases weakly with increasing magnetic field. The Cole-Cole plot [\c{hi}"(\c{hi}')] shows qualitatively and quantitatively identical features for HIIc and HIIab, independent of the orientation of the magnetic field with respect to the sample geometry and shielding current paths. The general features of \c{hi}"(\c{hi}') implies that, there is no flux creep for the range of frequencies and AC fields employed in this investigation. The maximum value of the loss peak and its position with respect to \c{hi}' in the Cole-Cole plot are largely consistent with the Bean critical state model. Slightly increased peak value in comparison to the predicted peak value within the Bean critical state model is probably due to a weak field dependence of Jc. The results obtained here are compared with various theoretical models and experimental findings. Prominent differences are noted and discussed in details in this study. △ Less

Submitted 29 May, 2021; originally announced May 2021.

Comments: Submitted for publication

Hole content dependent fluctuation diamagnetism in YBa2Cu3O7-δ: possible role of the pseudogap

Authors: Ayesha Siddika Borna, R. S. Islam, S. H. Naqib

Abstract: This study focuses on the temperature and hole content dependent fluctuation diamagnetism of hole doped YBa2Cu3O7-delta (Y123) high-Tc superconductors. Two different compositions of Y123 have been considered with in-plane hole content (p): 0.161 (optimally doped) and 0.143 (underdoped). The fluctuation induced excess diamagnetic susceptibility, Delta_chi(T), has been investigated via the mean-fiel… ▽ More This study focuses on the temperature and hole content dependent fluctuation diamagnetism of hole doped YBa2Cu3O7-delta (Y123) high-Tc superconductors. Two different compositions of Y123 have been considered with in-plane hole content (p): 0.161 (optimally doped) and 0.143 (underdoped). The fluctuation induced excess diamagnetic susceptibility, Delta_chi(T), has been investigated via the mean-field Gaussian-Ginzburg-Landau (MFGGL) formalism with and without a total energy cut-off in the fluctuating modes. It has been found that inclusion of total energy cut-off describes the Delta_chi(T) data significantly better. Furthermore, the pseudogap (PG) itself induces an anomalous decrease in the normal state magnetic susceptibility. By means of the analysis of Delta_chi(T)/T at different hole concentrations, we have explored the possible role of the PG on diamagnetic fluctuations. It has been found that MFGGL formalism is not able to reproduce the Delta_chi(T)/T features for the underdoped compound over a broad range of reduced temperature, Epsilon [= ln(T/Tc)]. The discrepancy becomes prominent in the temperature range where PG dominates the normal state magnetic susceptibility data. The agreement between the theoretical prediction and experimental Delta_chi(T) is better for the optimally doped compound with p = 0.161, where the effect of the PG is small. This notable difference implies that PG induced reduction in the magnetic susceptibility is not related directly to the superconducting fluctuations which in turn indicate that electronic correlations giving rise to the PG and Cooper pairing are independent to each other. △ Less

Submitted 19 May, 2021; originally announced May 2021.

Comments: Submitted for publication

A comprehensive DFT based insights into the physical properties of tetragonal Mo5PB2

Authors: M. I. Naher, M. A. Afzal, S. H. Naqib

Abstract: Tetragonal Mo5PB2 compound, a recently discovered superconductor, belongs to technologically important class of materials. It is quite surprising to note that a large number of physical properties of Mo5PB2, including elastic properties and their anisotropy, acoustic behavior, electronic (charge density distribution, electron density difference), thermo-physical, bonding characteristics, and optic… ▽ More Tetragonal Mo5PB2 compound, a recently discovered superconductor, belongs to technologically important class of materials. It is quite surprising to note that a large number of physical properties of Mo5PB2, including elastic properties and their anisotropy, acoustic behavior, electronic (charge density distribution, electron density difference), thermo-physical, bonding characteristics, and optical properties have not been carried out at all. In the present work we have explored all these properties in details for the first time with density functional theory based first-principles method. Mo5PB2 is found to be a mechanically stable, elastically anisotropic compound with ductile character. Moreover, the chemical bonding is interpreted by calculating the electronic energy density of states, electron density distribution, elastic properties and Mulliken bond population analysis. Mo5PB2 has a combination of mainly ionic, metallic, and some covalent bonding characteristics. The compound possesses high level of machinability. The band structure along with a large electronic density of states at the Fermi level reveals metallic character. Calculated values of different thermal parameters of Mo5PB2 are closely related to the elastic properties. The energy dependent optical parameters show close assent to the underlying electronic band structure. The optical absorption and reflectivity spectra and the low energy index of refraction of Mo5PB2 show that the compound holds promise to be used in optoelectronic device sector. Unlike the notable anisotropy found in elastic, mechanical properties and minimum thermal conductivity, the optical parameters are found to be almost isotropic with respect to the polarization direction of the incident electric field. △ Less

Submitted 11 May, 2021; originally announced May 2021.

Comments: Submitted for publication. arXiv admin note: text overlap with arXiv:2103.16027, arXiv:2005.10590