  In the present study we have investigated the structural properties,
electronic band dispersion, elastic constants, acoustic behavior, phonon
spectrum, optical properties, and a number of thermophysical parameters of
binary topological semimetal BaGa2 in details via first-principles calculations
using the density functional theory (DFT) based formalisms. The electronic band
structure and density of states calculations with spin orbit coupling reveal
semimetallic nature with clear topological signature. The minimum thermal
conductivities and anisotropies of the compound are calculated. The elastic
constants, phonon dispersion calculations show that the compound under study is
both mechanically and dynamically stable. Comprehensive study of elastic
constants and moduli shows that BaGa2 possesses fairly isotropic mechanical
properties, reasonably good machinability, low Debye temperature and melting
point. The chemical bonding in BaG2 is interpreted via the electronic energy
density of states, electron density distribution, elastic properties and
Mulliken bond population analysis. The compound possesses both ionic and
covalent bondings. The reflectivity spectra show strong anisotropy with respect
to polarization of the incident electric field in the visible to
mid-ultraviolet regions. High reflectivity over wide spectral range makes BaGa2
suitable as a reflecting material. BaGa2 is also an efficient absorber of
ultraviolet radiation. Furthermore, the refractive index is quite high in the
infrared to visible range. All the energy dependent optical parameters show
metallic features and are in complete accord with the underlying bulk
electronic density of states calculations. Most of the results presented in
this study are novel and should serve as useful reference for future study.
