  First-principles calculations within the density functional theory (DFT) with
GGA-PBE exchange-correlation scheme have been employed to predict the
structural, the elastic and the electronic properties of newly discovered
lithium silicide superconductor, Li2PtSi3, for the first time. All the
theoretical results are compared with those calculated recently for
isostructural Li2IrSi3. The present study sheds light on the effect of
replacement of transition metal element Ir with Pt on different mechanical,
electronic, and superconducting properties. The effect of spin-orbit coupling
on electronic band structure was found to be insignificant for Li2PtSi3. The
difference in superconducting transition temperatures of Li2PtSi3 and Li2IrSi3
arises primarily due to the difference in electronic energy density of states
at the Fermi level. Somewhat reduced Debye temperature in Li2PtSi3 plays a
minor role. We have discussed the implications of the theoretical results in
details in this study.
