Theory of the Self-Trapped Hole in the Alkali Halides

Abstract

Combining the self-consistent-field molecular-orbital results for the wave functions and energies of ${\mathrm{F}}_2^{-}$ and ${\mathrm{Cl}}_2^{-}$ with a classical calculation of the lattice distortion and polarization energies, we have obtained the ground- and excited-state potential curves of the $V_K$ center in several of the alkali halides. The widths and peak values of the optical-absorption bands have been calculated from these potential curves and are found to be in reasonable agreement with, but somewhat smaller than, the experimental results. The hyperfine constants are obtained as a function of internuclear distance and compared with the experimental results using the internuclear distance at the minimum of the configurational coordinate curves. The significance of the remaining discrepancies between theory and experiment for interpreting still unresolved aspects of the structure of $V_K$ centers is pointed out.