Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Effective-Hamiltonian parameters for \emph{ab initio} energy-level
  calculations of SrCl$_{2}$:Yb$^{2+}$ and CsCaBr$_{3}$:Yb$^{2+}$   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.

29
The categories of this paper are: funct-an
7
The categories of this paper are: hep-th
12
The categories of this paper are: nucl-th
33
The categories of this paper are: plasm-ph
17
The categories of this paper are: q-fin
18
The categories of this paper are: econ
0
The categories of this paper are: hep-ph
21
The categories of this paper are: adap-org
19
The categories of this paper are: eess
24
The categories of this paper are: dg-ga
34
The categories of this paper are: chem-ph
6
The categories of this paper are: astro-ph
15
The categories of this paper are: nucl-ex
1
The categories of this paper are: cs
30
The categories of this paper are: q-alg
36
The categories of this paper are: cmp-lg