Electron correlation effects on the f6-manifold of the Eu3+ impurity in Ba2 GdNbO6

The effects of atomic and molecular electron correlation and Gaunt interaction on the transition energies between the D-5(0) and F-7(1,2) levels, arising from the (4)f(6) State of the europium ion, have been studied for the ion and for the [EuO6](9-) cluster as it is found in the Ba2GdNbO6 crystal. The calculations were performed using the MOLFDIR program package. The results are compared to work previously done by Visser et al. in which correlation effects had not been taken into account. The effect of the Gaunt interaction is found to be small. An important contribution to the correlation energy emerges from the configuration represented by the double excitations from 4d to 4f. This in agreement with work performed by Jankowski and Sokolowski on Pr3+. The results are now in better agreement with experiment but are still not satisfactory. (C) 1995 John Wiley & Sons, Inc.