Lattice-Vibration Eigenvectors and Applications Thereof for NaCl and KCl

Eigenvectors and eigenvalues for vibrations of the rocksalt lattice were computed in the harmonic approximation on the rigid-ion model and on a deformation-dipole model. The eigenvectors are useful in visualizing the actual motion of the ions in the normal modes, and thence for classifying the modes. The eigenvectors, furthermore, provide a basis for perturbation treatment. With them we have computed the frequencies of the local modes, and the corresponding amplitudes of impurity-atom vibrations, that result from point mass defects in NaCl and KCl.