A comprehensive first principles calculations on (Ba0.82K0.18)(Bi0.53Pb0.47)O3 single-cubic-perovskite superconductor

In this present study, the pseudopotential plane-wave (PP-PW) pathway in the scheme of density functional theory (DFT) is utilized to investigate the various physical properties on (Ba0.82K0.18)(Bi0.53Pb0.47)O3 (BKBPO) single perovskite superconductor. We have analyzed elastic constants and moduli at zero and elevated pressures (up to 25 GPa) as well. We also have investigated the anisotropic nature incorporating both the theoretical indices and graphical representations in 2D and 3D dimensions, which reveals a high level of anisotropy. The flatness of the energy bands near EF is a sign of Van-Hf singularity that might increase the electron pairing and origination of high-TC superconductivity. The computed band structure exhibits its metallic characteristics is confirmed by band overlapping. A band of DOS is formed for the strong hybridization of the constituent elements. The orbital electrons of O-2p contribute most dominantly at EF in contrast to all orbital electrons. The orbital electrons at the EF are higher from both the partial density of states and charge density mapping investigation. The coexistence of the electron and hole-like Fermi sheets exhibits the multi-band nature of BKBPO. On the other hand, Fermi surfaces with flat faces promote transport features and Fermi surface nesting as well. The calculated value of the electron-phonon coupling constant ({\lambda} = 1.46) is slightly lower than the isostructural superconductor, which indicates that the studied BKBPO can be treated as a strongly coupled superconductor similar to the reported isostructural perovskite superconductors. Furthermore, the thermodynamic properties have been evaluated and analyzed at elevated temperature and pressure by using harmonic Debye approximation (QHDA).Comment: 20 pages, 7 figures, 6 table

Effects of pressure on the structural, mechanical, anisotropic, and electronic properties of

The variation of structural, mechanical, anisotropy, and electronic properties of $$\hbox {MgTi}_{{2}}\hbox {O}_{{4}}$$ with pressure up to 40 GPa have been studied by employing DFT based ab-initio    technique for the first time. The slight variation between the optimized and experimental lattice constant ensures the accuracy of the present work, and slightly decreased with pressure. The investigated zero pressure elastic constants and their linear response to pressure up to 40 GPa confirms the stability of cubic phase as the Born stability criteria are satisfied. A transition from cubic to tetragonal phase of $$\hbox {MgTi}_{{2}}\hbox {O}_{{4}}$$ is observed at 50 GPa pressure. The ductile nature of $$\hbox {MgTi}_{{2}}\hbox {O}_{{4}}$$ is exhibited in this study, which is enhanced with increasing pressure effect. The anisotropy factors are increased sharply with pressure indicating the changes of physical properties of $$\hbox {MgTi}_{{2}}\hbox {O}_{{4}}$$ in different directions under pressure. The band structure and density of states reveal the metallic nature of $$\hbox {MgTi}_{{2}}\hbox {O}_{{4}}$$, which can be slightly tuned under pressure. Therefore, our simulation results clearly elucidate the significance of taking into account the pressure effects on the physical properties of $$\hbox {MgTi}_{{2}}\hbox {O}_{{4}}$$

First-principles calculations to investigate pressure-driven electronic phase transition of lead-free halide perovskites KMCl3 (M = Ge, Sn) for superior optoelectronic performance

This article investigates the physical properties of lead-free tin- and germanium-based halide perovskites under pressure via the density functional theory to use as potential photovoltaic materials. Specifically, the structural, electronic, optical, and mechanical properties of KMCl3 (M = Ge, Sn) under diverse hydrostatic pressures ranging from 0 to 8 GPa are examined to vindicate the compounds' superiority for useful applications. The structures show high precision in terms of lattice constants, which approves the formerly published data. The calculated lattice constant (5.261 and 5.58 Å for KGeCl3 and KGeCl3, respectively, at 0 GPa) and unit cell volume (145.67 and 173.80 Å3 for KGeCl3 and KGeCl3, respectively, at 0 GPa) are significantly reduced ((lattice constant 4.924 Å (5.183 Å) and unit cell volume 119.41 Å3 (139.39 Å3) for KGeCl3 (KSnCl3) at 8 GPa) due to the pressure effect, while the cubic phase stability is maintained. Under ambient pressure, the calculated band gap reveals the compounds' semiconducting nature. Nevertheless, when pressure is increased, the band gap narrows, enhancing its conductivity and igniting its route towards semiconductor to metallic transition. The ionic and covalent bonding nature of K-Cl and Ge(Sn)-Cl, respectively; as well as the decrement of bond length due to external pressure are marked by charge density mapping. The optical functions are also enhanced when pressure is devoted, vindicating the chosen perovskites' suitability in various optoelectronic devices in the visible and ultraviolet ranges. Likewise, while maintaining mechanical stability, hydrostatic pressure significantly impacts mechanical properties. The ductility and anisotropic behavior of both perovskites are intensified under applied pressure