  The topological Weyl semimetal CaSn3, belonging to the AuCu3 type cubic
structure, is an important electronic system to investigate both from the point
of view of fundamental physics and prospective applications. In this work, we
have studied the structural, elastic, mechanical, electronic, bonding, Fermi
surface and optical properties of CaSn3 in detail using the density functional
theory. A comprehensive study of elastic constants and moduli shows that CaSn3
possesses low level of elastic anisotropy, reasonably good machinability, mixed
bonding characteristics with ionic and covalent contributions, brittle nature
and relatively high Vickers hardness with a low Debye temperature. Analysis of
bond population supports the bonding nature as indicated by the elastic
parameters. The bulk electronic band structure reveals clear semimetallic
features with signature Dirac cone-like dispersions near the Fermi level. A
pseudogap in the electronic energy density of states at the Fermi level
separating the bonding and the antibonding peaks points towards significant
electronic stability of cubic CaSn3. The Fermi surface mostly consists of
electron-like sheets with very few small hole pockets. The band structure is
fairly isotropic in the k-space. The optical constants show interesting
characteristics. The reflectivity spectra show almost non-selective behavior
over a wide range of photon energy encompassing infrared to mid-ultraviolet
regions. High reflectivity over wide spectral range makes CaSn3 a suitable
material for reflecting coating. CaSn3 is an efficient absorber of ultraviolet
radiation. The refractive index is very high in the infrared to visible range.
All the energy dependent optical parameters exhibit clear metallic signatures
and are in complete accord with the underlying bulk electronic density of
states calculations.
