An ab initio estimate of correlation effects on the band gap of covalent semiconductors: diamond and silicon

An ab initio scheme, which has previously been used to determine electron-correlation effects on valence-band splittings in semiconductors, is extended to yield the correlation-induced shift of the upper valence-band edge in diamond and silicon. Assuming that the processes of removing/adding one electron from/to the solid causes symmetric correlation effects, this information allows for an estimate of correlation contributions to band gaps. Reasonable agreement with experiment is obtained.