First‐Principles Calculation of Deformation Potentials of Copper Halides

Self‐consistent, relativistic LMTO band structure calculations, using the local‐density approximation, are performed for strained CuCl and CuI crystals in the zinc‐blende structure. Equilibrium volumes and bulk moduli are derived. Calculations for uniaxially strained crystals are used to deduce deformation potentials for splitting of the Γ 15 ‐state (top of the valence band) with and without spin—orbit coupling (SO). In case of trigonal strain, these quantities are calculated as a function of the internal‐strain parameter ζ. It is shown that the deformation potentials can be evaluated by moving the potentials obtained by one self‐consistent calculation for the unstrained crystal to the lattice positions of the strained crystal. The inclusion of SO is important in the calculation of the trigonal‐shear deformation potentials but affects only slightly those for tetragonal strain.