Wednesday, July 24, 2013

1307.5953 (A. J. Salkeld et al.)

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

A. J. Salkeld, M. F. Reid, J. -P. R. Wells, G. Sanchez-Sanz, L. Seijo, Z. Barandiaran
Calculated energy levels from recent \emph{ab initio} studies of the electronic structure of SrCl$_{2}$:Yb$^{2+}$ and CsCaBr$_{3}$:Yb$^{2+}$ are fitted with a semi-empirical "crystal-field" Hamiltonian, which acts within the model space $4f^{14} + 4f^{13}5d + 4f^{13}6s$. Parameters are obtained for the minima of the potential-energy curves for each energy level and also for a range of anion-cation separations. The parameters are compared with published results parameters fitted to experimental data and to atomic calculations. The states with significant $4f^{13}6s$ character give a good approximation of the impurity-trapped exciton states that appear in the \emph{ab initio} calculations.
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