Effective-Hamiltonian parameters for \emph{ab initio} energy-level calculations of SrCl$_{2}$:Yb$^{2+}$ and CsCaBr$_{3}$:Yb$^{2+}$

摘要

Calculated energy levels from recent \emph{ab initio} studies of theelectronic structure of SrCl$_{2}$:Yb$^{2+}$ and CsCaBr$_{3}$:Yb$^{2+}$ arefitted with a semi-empirical "crystal-field" Hamiltonian, which acts within themodel space $4f^{14} + 4f^{13}5d + 4f^{13}6s$. Parameters are obtained for theminima of the potential-energy curves for each energy level and also for arange of anion-cation separations. The parameters are compared with publishedresults parameters fitted to experimental data and to atomic calculations. Thestates with significant $4f^{13}6s$ character give a good approximation of theimpurity-trapped exciton states that appear in the \emph{ab initio}calculations.