Inclusion of configuration interaction through the use of second-order perturbation theory in the calculation of the 364×364 energy matrix for Nd${}^{3+}$ in Nd${}^{3+}$:YAG and Nd${}^{3+}$:LiYF${}_4$ is shown to improve agreement with experimentally observed polarized UV-VIS absorption spectra significantly. The effect of taking account of electric-dipole and inhomogeneous dielectric mechanisms has been assessed in calculating the polarized oscillator strengths. The A${}_{\mathrm{tp}}$ parameters have been calculated by direct summation over the multipole-expanded environments, and the polarized oscillator strengths calculated for a sequence of molecular-dynamics generated environments. The correlation coefficients are 0.55, 0.61, and 0.63 for Nd${}^{3+}$:YAG, $\sigma$-polarized Nd${}^{3+}$:LiYF${}_4,$ and $\pi$-polarized Nd${}^{3+}$:LiYF${}_4$, respectively.

• Received 13 March 1997

DOI:https://doi.org/10.1103/PhysRevB.56.13006