Theoretical calculation for the phonon spectrum and thermodynamic functions of vanadium and its hydride

Abstract

Based on density functional theory(DFT), using virtual crystal approximation and generalized gradient approximation(GGA)with pseudopotential method, the lattices and energies for five crystallines of vanadium hydrides are optimized and calculated. The phonon densities of states are calculated based on density functional perturbation theory(DFPT). The standard Heat capacities, Entropies, Helmholtz free energies and Gibbs functions of vanadium and its hydride are deduced at 298.15K. The calculated results are discussed and compared with experimental data.