An alternative semicontinuum model for the F center in alkali halides

In this paper, we propose a semicontinuum model for the F center "alternative" to the Simpson semicontinuum and point-ion models, which at present are used to perform calculations concerning various properties of this center. The model mainly assumes the F center to be an electron within a spherical box with penetrable walls. The Schrödinger equation is solved assuming the potential inside the box to be the same as that used by Simpson (corrected by Krumhansl and Schwartz); the Coulombian tail outside the box is not taken into account. The radius of the box is varied in order to fit the 1s-2p transition energy. We have determined for this system the eigenfunctions and energy eigenvalues for the lowest states, as well as the oscillator strength for the F band. The results are in good agreement with those reported in the literature.