Energy Bands of Copper Chloride I. Theory

A calculation of the energy bands of CuCl has been performed in which several innovations and refinements were made to previous procedures. In this paper the method used in the calculation is described. The combined plane‐wave tight‐binding (“mixed‐basis”) method of Kunz was adapted to the zinc blende lattice. Tight‐binding functions were truncated so as not to overlap one another, as suggested by Deegan and Twose. Overlap between these functions and the short‐range potential (which was not truncated) of neighboring ions was significant and so was included. A semiempirical approach was devised which involved adding a square‐well potential of adjustable strength to each ionic potential. In order to obtain coefficients of p‐like and d‐like contributions to a given eigenfunction, a technique was devised for projecting these from the plane waves.