Screened exchange calculations of semiconductor band structures.

We have calculated the band structures of several group IV and III-V semiconductors from first principles. The technique we have employed is the screened exchange method, which is an extension of the commonly used Kohn-Sham density functional theory (DFT). In standard DFT, exchange and correlation effects are usually treated with the local density (LDA), or generalised gradient (GGA), approximations. While good structural properties can be obtained for most materials with these approximations, the electronic band-gap is often severely underestimated. The screened exchange method employed here treats exchange non-locally, in a similar manner to the Hartree-Fock method. We find that the screened exchange method significantly improves results in most cases, although the computational cost is somewhat higher