Structural effects on the calculated semiconductor gap ofCrSi2

The results of band calculations for hexagonal ${\mathrm{CrSi}}_2$, carried out in the local-density approximation, predict an indirect semiconductor gap of 0.30 eV which is in excellent agreement with the measured optical value (∼0.35 eV). The calculated gap, which occurs within the Cr 3d manifold, is particularly sensitive to the local Cr-Si coordination geometry. It decreases with uniaxial pressure along c and vanishes for the alternative sequencing of hexagonal-type ${\mathrm{CrSi}}_2$ layers that characterize the orthorhombic and tetragonal phases of the refractory (groups IV–VI) transition-metal disilicides.