  In this paper, we have presented a comprehensive study of the physical
properties of Kagome superconductor CsV3Sb5 using the density functional theory
(DFT). The structural, mechanical, electronic, atomic bonding, hardness,
thermodynamic, and optical properties, and their pressure dependences have been
investigated for the first time. The calculated ground state lattice parameters
and volume are in excellent agreement with available experimental results. The
estimated single-crystal elastic constants ensured the mechanical stability of
the compound, whereas phonon spectra endorse dynamical stability at zero
pressure. The electronic band structure, energy density of states, optical
properties confirmed the metallic features. The Pugh ratio, Poisson's ratio of
the compound revealed softness and ductility. The hardness, estimated from
several formulae, is quite low while the machinability index predicted good
machinability with excellent dry lubricating properties. The compound shows
tendency towards structural instability at a pressure around 18 GPa. The
optical constants have also been studied to correlate those with electronic
properties and to predict possible applications of this compound. Both
mechanical and optical properties show anisotropy.CsV3Sb5 is predicted to be an
efficient absorber of ultraviolet radiation. The compound is also an efficient
reflector of visible light.
