Configuration-Interaction Effects on the ``Free-Ion'' Energy Levels of Nd3+ and Er3+

Abstract

By the use of three or four parameters of configuration interaction, the experimental ``free‐ion'' energy levels of Nd3+ and Er3+ have been fitted with an rms deviation of 45–55 cm−1. The significance of the various parameter values is discussed. It is also shown that assignments based purely on comparison with a calculation using only F 2, F 4, F 6, and ζ may occasionally be in error. Several discrepancies in previous work are now cleared up.