Nonlocal exchange and correlation and semiconductor band structure

We present the results of self-consistent band-structure calculations for bulk GaAs, in which the density-functional theory is applied with a nonlocal expression for the exchange and correlation energy, $E_{\mathrm{xc}}\left[n\right(\overrightarrow{\mathrm{r}}\left)\right]$. Using the same ionic potentials and basis set, other local expressions for exchange and correlation are also considered for comparison. It will be shown that the inclusion of nonlocality in the exchange and correlation potential improves the description of the valence bands, but does not solve the "gap problem" experienced by the simpler local expressions (i.e., too small a gap).