Full-potential linear-muffin-tin-orbital calculation of phonon frequencies in semiconductors

The optical-phonon frequencies in compound semiconductors are obtained from total-energy calculations using the local-density approximation in conjunction with a newly developed full-potential version of the linear-muffin-tin-orbital (LMTO) method. In this scheme the full nonsphericity of the potential is included throughout the self-consistency cycle. The results agree well with experiments and with the results of first-principles pseudopotential calculations. A linear correlation is found between the force constants and the ${\mathrm{sp}}^3$ bond orders as obtained, for instance, from conventional LMTO calculations for the undistorted crystals. This allows us to derive the optical-phonon frequencies for all zinc-blende-type semiconductors from those of only two materials, e.g., Si and Ge.