Ab Initio Calculations of the Multiplet Terms of (TmP4)3+ Cluster

Multiplet structures of a rare earth ion, Tm3+, in tetrahedral symmetry of ligand P atoms are calculated on the basis of configuration interaction calculation with Gaussian basis sets. The spin-orbit interactions of a rare earth ion and the crystal field effect are all taken into account in the ab initio calculations. The calculated results of the splitting between the ground state and excited multiplet states, 3H4x3H6 and 3H5x3H6, are in good agreement with the former numerical and experimental results.