MUFFIN-TIN APPROXIMATION IN CALCULATION OF ELECTRONIC BAND STRUCTURE

Several standard techniques for the calculation of electronic band structures in solids seem to require the crystal potential to be of 'muffin-tin' form, but an elementary calculation shows that contributions from variations of the potential in the interstitial region may easily be included in the secular determinants of the augmented plane wave and Korringa-Kohn-Rostoker-Ziman methods. The corrections in the Korringa-Kohn-Rostoker formalism are more complex. A numerical example for germanium shows that these terms can be significant.