Application of the method of coherent states to the optical properties of Fe²⁺ in ZnSe

It is well known that the system ZnSe: Fe²⁺ shows more than one zero-phonon line in the infrared luminescence spectra. This is a clear manifestation of the Jahn-Teller effect for this and other similar systems. So far the quantitative description of this phenomenon has relied on methods developed from the weak-coupling limit. In the present paper we apply an alternative method developed recently to deal with this vibronic coupling. The vibronic basis is contructed in the limit of strong coupling by means of coherent Glauber states. Vibronic functions with increasing number of vibrational quanta N are considered. The diagonalization of a linear Jahn-Teller Hamiltonian is then performed. Good agreement between our calculations and the experimental data for ZnSe: Fe²⁺ available in the literature is found. A study of the line-space is also performed. The stability of the solutions with respect to N is analyzed. The application discussed here is a good test for the new method, so the advantageous and disadvantageous of it are also brought out. The possible extension of this work for the cases of ZnSe: Fe²⁺ and CdTe: Fe²⁺ is finally discussed.