Jahn-Teller effect with the recursion method: Dipole-carrying states and the absorption spectrum of CdTe:Fe2+

We have theoretically analyzed the Jahn-Teller effect in the near-infrared absorption spectrum of ${\mathrm{Fe}}^{2+}$ ions in CdTe. We have assumed a linear active interaction on the ${}_{}{}^5{}_{}{}^{}\mathrm{T}_2^{}{}_{}{}^{}$ levels of the 3$d^6$ electrons of the ${\mathrm{Fe}}^{2+}$ impurity; the phonon symmetry taken into account is ${\Gamma }_3$. The spin-orbit interaction has also been included. By means of the recursion method and an appropriate choice of the dipole-carrying initial state, we have calculated in a nonperturbative way the absorption spectrum of ${\mathrm{Fe}}^{2+}$ ions in CdTe, including a large number of phonons. The theoretical absorption spectrum and some temperature-dependent features are discussed and compared with the available experimental data.