Slater transition-state band-structure calculations

Slater's transition-state method enables one to calculate excitation energies by means of an artificial state that is halfway between the ground state of an atom or molecule and an excited state. This idea has been adapted to insulators and semiconductors with a band-structure model where a localized hole is created in one cell by removing charge from the top of the valence band and putting it in a delocalized state at the bottom of the conduction band. Significant improvements in calculated band gaps are obtained in most cases over conventional local-density calculations.