First principles calculations of structural, thermophysical, dynamical, electronic and optical properties of the intermetallic compound CoSi

Abstract

Cobalt monosilicide has attracted significant attention due to the topological nature of its electronic band structure. Apart from electronic structure analyses, most of the fundamental physical characteristics of CoSi, including its elastic, mechanical, acoustic, thermophysical and optical properties, have not yet been thoroughly examined. For the first time, this work explores these yet unexamined properties through density functional theory (DFT) based first-principles approach. Analyses of calculated elastic properties indicate that CoSi is a mechanically stable, machinable, ductile and comparatively hard material with the existence of metallic/ionic bonding between atoms. No imaginary or negative frequency branch exists near the high symmetry points, which implies that the structure is dynamically stable. The investigation of thermophysical properties, including Debye temperature, acoustic properties, Grüneisen parameter, heat capacity, thermal expansion coefficient, melting temperature and dominant phonon mode, also suggests the hard nature of CoSi. The electronic band structure and density of states calculations reveal metallic behavior with clear topological signature. The optical parameters are analyzed across various photon energies. CoSi exhibits excellent reflective nature over a broad band of photon energies. The compound also absorbs ultraviolet radiation efficiently. Moreover, the refractive index of the compound is relatively high in the low energy levels. All the optical parameters display metallic characteristics and are entirely consistent with the electronic density of states calculations.