Comprehensive first-principles calculations on physical properties of ScV2Ga4 and ZrV2Ga4 in comparison with superconducting HfV2Ga4

Abstract

We use first-principles method for a comprehensive investigation of structural, elastic, electronic, Mulliken atomic population based bonding, phonon, thermodynamic and optical properties of ScV2Ga4 and ZrV2Ga4 in comparison with the isostructural HfV2Ga4 superconductor. The single and polycrystalline elastic constants are all evaluated and discussed. Cell stability employing elastic constants criteria, formation enthalpy and phonon dispersion are verified. Brittleness and hardness features are also discussed. Elastic anisotropies are evaluated and discussed to unravel some of the macroscopic behaviors of the studied compounds. The significant overlapping between conduction and valence bands in the vicinity of Fermi level (EF) confirms the metallic characteristics for MV2Ga4 (M = Hf, Sc, Zr). It is predicted that the TDOS around the EF arises mostly from V–3d with a smaller contribution of Ga–4p states. The Fermi surfaces show multiband nature but that of ScV2Ga4 has different and complex shape in contrast to ZrV2Ga4 and superconducting HfV2Ga4. The bonding characteristics are analyzed using the energy band structure, charge density distribution and Mulliken atomic and bond overlap population. Such analysis exhibits directional electronic density-channel, highly populated 1D V leashed in (100) plane in the lattices. The formation of such V-chains which accumulate the highest electronic charge might generate Cooper pairs to exhibit superconducting behavior in the yet unobserved Sc and Zr containing compounds. The phonon dispersion curves, phonon density of states and optical phonon frequencies, Raman and infrared activities of the materials are discussed for the first time. The temperature dependent thermodynamic properties including heat capacity at constant pressure are calculated as a function of temperature and compared with the available data. Various optical properties are calculated and their features are analyzed. The potentials of the compounds for practical uses as coating materials to reduce solar heating and enhance radiative cooling are also mentioned.