  A large number of hitherto unexplored elastic, thermophysical, acoustic, and
optoelectronic properties of a double Weyl semimetal SrSi2 have been
investigated in this study. Density functional theory (DFT) based methodology
has been employed. Analyses of computed elastic parameters reveal that SrSi2 is
a mechanically stable, ductile, moderately machinable, and relatively soft
material. The compound is predicted to be dynamically stable and possesses
significant metallic bonding. Study of thermophysical properties, namely, Debye
temperature, Gr\"uneisen parameter, acoustic parameters, melting temperature,
heat capacity, thermal expansion coefficient, and dominant phonon mode is also
indicative of soft nature of SrSi2. The electronic band structure calculations
without and with spin-orbit coupling disclose semimetallic character with clear
Weyl nodes close to the Fermi level. The electronic dispersion is anisotropic
characterized by nearly flat and linear regions within the Brillouin zone.
Optical parameters at different photon energies are investigated. SrSi2 shows
excellent nonselective reflection spectrum across an extended range of energy
encompassing the visible region implying that the compound under study has
significant potential to be used as an efficient solar energy reflector. SrSi2
absorbs ultraviolet light quite efficiently. The compound also possesses high
refractive index in the low energy. All these optical features can be useful in
optoelectronic device applications.
