Quantum chemical cluster modeling of boundary conditions for metal azides

An approach to crystal field modeling for solids with a predominantly ionic type of bond is suggested. The approach uses Evjen's method of iteratively selecting point charges in such a way that the net charge on the crystal f ragment be close to zero. The MNDO quantum chemical program is modified to include electron interactions of a point charge system in the Fock operator . The approach is tested on potassium azide. The calculated charges on pota ssium atoms agree well with the results of band structure calculations.