The Korringa-Kohn-Rostoker method and momentum density calculations in solids

Abstract

The authors point out an omission in an often used form of the variational functional in the Korringa-Kohn-Rostoker method of electronic band structure calculation. This omission does not affect the results of Kohn and Rostoker, but leads to incorrect results for matrix elements calculated from the variational functional for a crystal with more than one atom per unit cell and muffin-tin spheres of unequal sizes. They also discuss the form of the momentum density and its behaviour in the vicinity of free-electron energies.