Recent Studies of Localized Modes in Crystals

Abstract

Some recent simulations of localized vibrational modes associated with substitutional impurities in crystals are discussed. Most of the examples are for impurities in III–V semiconductors and alkali halides, cases for which improvements in measurement and sample preparation techniques have generated new exacting tests for theoretical models. The displacements of atoms in the modes are revealed by the fine structure from isotopes of both the impurity and the host crystal atoms. Available schemes for modelling these dynamical properties of defects are reviewed.