Abstract
The electronic energy band structures of diamond-type crystals (C, Si, Ge, and α-Sn) are calculated by use of extended Hückel theory, taking into account all interactions between atoms up to the sixth neighbors. Reasonable overall agreement is obtained with experiments or other calculations when the four parameters included are adjusted to fit the experimental energies at two points in the Brillouin zone, zone center and conduction band minimum. This suggests the possibility of a reliable utility of this method for the systematic study of electronic structures of Si, Ge, and α-Sn as well as diamond.