Electronic States of the <i>F</i>-Center in Lithium Fluoride. II

Abstract

The electronic structure of the F -center in LiF is investigated by making use of a variational wave function for the trapped electron which is orthogonal to all the ion-core functions. The variational parameters are so determined as to minimize the total energy of the whole crystal, including exchange interactions, polarization effects and van der Waals interactions. The equilibrium positions of the surrounding ions and the ion-core dipoles are determined in a self-consistent manner with the F -center wave functions. The resulting wave function shows correct oscillatory behaviors around each nucleus. The calculated first optical excitation energy is in excellent agreement with experiment. The associated oscillator strength is also evaluated. The line-width of the electron spin resonance is computed, yielding a value twice as large as the experimental value. A source of this discrepancy and other sources of errors which might have affected the energy levels are examined.