Exchange charge model and analysis of the microscopic crystal field effects in KAl(MoO4)2:Cr3+

In the present paper, we report on consistent crystal field calculations of the Cr3+ ions energy levels in KAl(MoO4)2 using actual D3d site symmetry of the Cr3+ position and employing the exchange charge model (ECM) of the crystal field. In addition to the energy level calculations, the Huang–Rhys factor S=5.7 and effective phonon energy ℏω=268 cm–1 were evaluated in the single configurational coordinate model. Detailed treatment of the microscopic crystal field effects in the ECM framework allowed to obtain analytical dependence of the crystal field strength 10Dq on the Cr–O interionic distance and extracting from it the values of some parameters of the electron–vibrational interaction (EVI) in the KAl(MoO4)2:Cr3+ system. All obtained results are compared with experimental data and discussed; agreement between the calculated and experimental parameters is good.