The electronic structure of diamond, silicon and germanium

The equivalent orbital method of describing the electronic structure of valence crystals, introduced in an earlier discussion of diamond, is extended in various ways. The interactions of more distant bonds are now included so that a more detailed description of the electronic structure can be given. The role of the equations as interpolation formulae is illustrated and used to deduce the effective masses of holes for diamond, silicon and germanium. The application of the method to the conduction bands is also considered.