Oscillator strength calculations for Nd2O3 and Nd3+:LiYF4

In contrast to earlier work based on least-squares fitting of crystal-field (CF) parameters to experiment, the current study diagonalizes the complete 364 x 364 energy matrix directly using a simple CF model using only four free parameters, These are the Slater integrals F-2, F-4, F-6 and the spin-orbit coupling constant zeta. The various polarizabilities and shielding parameters have been derived by ab initio methods [2]. All Stark levels within the Nd3+(4f(3)) configuration are presented. The calculated Stark splittings agree well with experiment for the Nd3+ ion in both Nd2O3 and Nd3+:LiYF4; however the agreement is not so good at higher energies. This is expected when configuration interaction is neglected. The eigenvectors of the complete energy matrix are used to calculate polarized oscillator strengths. For the case of Nd3+:LiYF4, our results indicate that the local structure around the Nd3+-ion contracts compared to the structure around the Y3+-ions.