Phase stability, mechanical, electronic, magnetic and optical properties of tetragonal and cubic M₃V (M: Pd, Pt)...

The full potential linearized augmented plane wave (FP-LAPW) method was used to investigate the ground states as well as the mechanical, electronic, magnetic and optical properties of M₃V (M: Pd, Pt) compounds. The generalized gradient approximation (GGA) of Perdew-Burke and Ernzerhof (PBE-GGA) is employed to treat the exchange-correlation potential for all the calculations except for structural properties where both Wu and Cohen generalized gradient approximation (WC-GGA) and Perdew and Wang local spin density approximation (LSDA) have been added. The cohesive energies, the formation enthalpies and the densities of states at the Fermi level N(E_F) show that the D0₂₂ structure is more stable than D0₂₃ and L1₂. The lattice parameter and bulk modulus results agree well with the available experimental measurements and theoretical predictions. The elastic and mechanical properties are predicted and show that both compounds exhibit ductile behavior. Furthermore, our calculations of Debye and melting temperatures are in good agreements with experimental results reported in the literature. The densities of states (DOS) show that strong d-d hybridization is behind the formation of the pseudogap at the Fermi level. The contours of the valence charge densities show combinations of metallic and covalent bonds. The number of bonding electrons per atom n_b, the electronic specific heat coefficient γ, and the electron-phonon coupling constant λ, are determined. The obtained values of the magnetic moments and polarization coincide with the reported values for both D0₂₂ and L1₂ structures. Moreover, the optical properties, including the dielectric functions, extinction coefficient K(ω), reflectivity coefficient R(ω) and energy loss function L(ω) are studied in the range of 0-14 eV.