Self-Consistent Energy Bands and Cohesive Energy of Potassium Chloride

The valence and conduction bands of potassium chloride were determined by the augmented-plane-wave method from a potential of a more general functional form than that usually assumed in this method. With a few iterations of the band calculation within the Hartree-Fock-Slater (HFS) approximation, a good degree of self-consistency was obtained. The calculation of the cohesive energy of the crystal from the energy-band results was simplified considerably by using Slater's approximation to the exchange potential in the exchange-energy terms, and the resulting cohesive energy is in excellent agreement with experiment. The self-consistent HFS values of the $\mathrm{Cl} 3p$ bandwidth and the band gap were found to be 0.82 eV and 6.3 eV, respectively.