Ab initio calculation of the phonon frequencies in silicon using small atomic clusters

An ab initio pseudopotential local density functional calculation is performed on Si 5 H 12 to determine its equilibrium structure and the energy for a number of slightly distorted structures. The parameters of a Keating potential are then found by a least-squares fitting to these energies. The photon frequencies of the bulk solid are derived from this potential and found to be in reasonably good agreement with the experimental results.