COLOUR CENTRES, GENERAL.THE Vk CENTER IN CESIUM HALIDES

The properties of the Vk center in cesium halides are investigated on the basis of the small polaron model. To observe the stability of the Vk center, relaxation energies are computed both for the hole localized on a single site and for the Vk center. The activation energies of the 180° jump and 90° jump are estimated using the simplest approximation. The static properties are successfully explained and the importance of acoustic mode interactions in the self-trapping is shown. For the jumping motion, the results indicate that more detailed studies are required