LaPt2B2C: A conventional borocarbide superconductor

Local-density-approximation electronic-structure calculations for the recently discovered ${\mathrm{LaPt}}_2$ ${\mathrm{B}}_2$C superconductor are reported. The calculations show, as in ${\mathrm{LuNi}}_2$ ${\mathrm{B}}_2$C, that despite the quasi-two-dimensional crystal structure, the electronic structure in the vicinity of the Fermi energy (${\mathit{E}}_{\mathit{F}}$) is quite three dimensional, with substantial contributions from all atoms. In this compound, ${\mathit{E}}_{\mathit{F}}$ falls on the low-energy side of a peak in the electronic density of states, suggesting that ${\mathit{T}}_{\mathit{c}}$ may be increased by doping to a higher electron count. The value of the density of states at ${\mathit{E}}_{\mathit{F}}$ is found to be substantially smaller than that of ${\mathrm{LuNi}}_2$ ${\mathrm{B}}_2$C in agreement with experiment.