Calculated shifts in electronic states for fcc hydrogen

Abstract

First-order shifts in electron energy levels at $k_F$ and at high-symmetry points are calculated for hypothetical fcc hydrogen using a perturbation procedure in conjunction with the modified-plane-wave method. The shifts are calculated for hydrostatic, tetragonal, and trigonal strains. For hydrostatic compression the general trend is that levels $\lesssim E_F$ shift downward while levels $\gtrsim E_F$ shift upward; there is a general widening of the gap between first and second bands. For the shear cases the numerical results satisfy symmetry requirements where tested. For comparable strain parameter $e$ the shifts at $E_F$ under shear are considerably larger than in the hydrostatic case.