Correlation crystal field analyses with orthogonal operators

Abstract

The construction of orthogonal operators to represent correlation crystal field (CCF) effects in the f N configuration of lanthanide and actinide ions is discussed. The approach of B. R. Judd [J. Chem. Phys. 66, 3163 (1977)] is extended to make all the operators orthogonal. The spin-correlated crystal field (SCCF) parametrization that has been successful in removing several long-standing anomalies from crystal field fits involves only two of the two-electron orthogonalized operators. We calculate values of the orthogonal CCF parameters from recent ab initio results. On the basis of these calculations the sixth rank SCCF operators are predicted to be very important. Fits using various combinations of the CCF parameters are reported for Ho3+ and Gd3+in LaCl3. For these systems we only obtain consistent results for the parameters associated with the sixth rank SCCF.