Anisotropic breathing shell model and phonons in NaCl structures

Callow, Diller and Norgett, in their investigations on the dynamics of alkali halides, have developed analytic potentials for the short range interactions between the anions and cations. These potentials consisting of Buckingham and van der Waals contributions have been determined from the elastic, dielectric constants and the equilibrium conditions of the lattice and are found to satisfactorily explain the defect properties of many halides. We employ the analytic potentials of Catlow et al. and use anisotropic breathing corrections for the computation on phonon dispersions and Debye-Waller factors of all NaCl structure alkali halides. The results of our study show that good agreement can be obtained with these more physical parameters.