The structural, electronic, mechanical, lattice dynamics and thermodynamic properties of Rh5B4: First-principles calculations

The structural, electronic, vibrational, mechanical and thermodynamic properties of Rh5B4 have been investigated within the framework of the density functional theory (DFT) and the direct method using first-principles calculations. The calculated lattice parameters are in good agreement with the available experimental data. The electronic structure suggests that Rh5B4 should exhibit the metallic behavior and hybridizations exist between Rh-d and B-s, B-p orbitals, which illuminates that the bonding between them has certain covalent character. Mechanical properties including elastic constants, bulk modulus, shear modulus, Young’s modulus, and Poisson’s ratio [Formula: see text] are calculated. Phonon dispersions and phonon density of states (DOS) are obtained, respectively. Our results indicate that Rh5B4 is dynamically and mechanically stable with better ductility (B/G = 3.28) at ambient pressure. In addition, the phonon frequencies at the center ([Formula: see text] point) of the first Brillouin zone are predicted and Raman-active and infrared-active modes are also assigned. Finally, the phonon contribution to the Helmholtz free energy F, the phonon contribution to the internal energy E, the constant volume specific heat Cv and vibrational entropy S are studied over the range 0 [Formula: see text] 1000 K.

Metal hydrogen sulfide superconducting temperature

AbstractÉliashberg theory is generalized to the electronphonon (EP) systems with the not constant density of electronic states. The phonon contribution to the anomalous electron Green’s function (GF) is considered. The generalized Éliashberg equations with the variable density of electronic states are resolved for the hydrogen sulphide SHThe results of the solution of the Eliashberg equations for the Im-3m (170 GPa), Im-3m (200 GPa) and R3m (120 GPa) phases are presented. A peak value T