Details of the band gap and band widths within materials are of fundamental
importance to a wide range of applications. A hybrid scheme is used to pre
dict the band gaps of a variety of materials. The electronic structure of s
ilicon is examined in some detail and comparisons with alternative theories
are made. Agreement with experimentally derived band gaps is at least as g
ood as that obtained with sophisticated correlated calculations or perturba
tion theories. The functional is straightforward to implement, computationa
lly efficient and produces ground state energy surfaces which are significa
ntly more accurate than those computed using the best gradient corrected de
nsity functionals currently in use. (C) 2001 Elsevier Science B.V. All righ
ts reserved.