Calculation of Optical Gaps in Silicon in the Screened Exchange-Coulomb Hole Approximation

摘要

The electronic excitation energies have been calculated for Si using the ab initio pseudopotential approach and the screened exchange-coulomb hole approximation for the electron self energy. Within the approximation of neglecting local field effects in screening the coulomb interaction, the direct gaps are found to be in much better agreement with experiment than standard density functional calculations. We argue that the inclusion of local field effects are necessary to reproduce the band dispersions and hence the indirect gap. (ERA citation 11:016729)