Multiplet Structure Calculations for Rare Earth Ions

Abstract

We obtain the multiplet energies for several rare earth (RE) ions by ab initio molecular orbital calculations including the spin-orbit interaction working on 4f electrons of RE. Because of a limitation of the ability of computations, the lower lying multiplet energies for Ce³⁺, Nd³⁺, Eu³⁺, Gd³⁺ and Er³⁺ ions were calculated in this report. For the excitations of 4f electrons, the spin multiplicity in the multiplet terms for 4f ⁿ electrons does not hold (not always ΔS=0) both in initial and final states by mixing different S states upon spin-orbit interaction. We estimated the possibility of the transitions for the multiplet terms for RE ions with use of the obtained electronic spin states of the 4f electrons.