Jahn-Teller effect in ZnS:Fe²⁺: A comparison between the method of Glauber states and Born-Oppenheimer states

The absorption spectra of magnetic impurities in II-VI compounds can only be explained if the Jahn-Telller effect is taken into account. To cope with this task there is a variaty of methods. In the present work we compare two of them: Born-Oppenheimer method and Glauber states method. The application makes use of the parameters that would be appropriate for the absorption spectrum of ZnS:Fe²⁺. The only free parameter in our calculations is the Jahn-Teller energy, so we do not attempt here a final description of the spectrum. The emphasis is on the comparison of both methods looking for their validity and divergence conditions and especially the way in which they can reinforce each other to give a more reliable description of these spectra.