Local fields and electric dipole moment of localized impurities in crystals

Abstract Dipole transition matrix elements of impurity centres are estimated accounting for the “acting” electric field in the crystal Ea. Ea is shown to depend on the type of wave functions and radii of states among which the transition occurs. Some examples where Ea is essential are considered. It is found, for example, that the dipole moment of the localized electron is expressed via oscillator forces submitted to the sum rule only in the case when the radius of electron state is large enough. A corresponding criterion is given. The examination of matrix elements in the dipole transitions of off‐centre ions shows that in this case the acting field is near to the Lorentz field.