Crystal-Field Splittings of f3 Systems: Covalency Effects

Abstract
Using a simple molecular‐orbital method, we have determined the A 4 0 〈r 4 〉 and A 6 0 〈r 6 〉 crystal‐field parameters for both the Nd3+(4f 3)‐ and U3+(5f 3)‐doped CaF2 systems. We have compared these theoretical parameters to those derived experimentally from fits to the observed energy‐level structures. We also have calculated these parameters using the point‐charge lattice‐sum model. The molecular‐orbital treatment yields the better results.