  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).
