Wave Functions forFCenters in MgO

Abstract

A calculation of the ground ${{\Gamma }_1}^e$ and first excited ${{\Gamma }_4}^o$ states of the simple $F$ center in MgO is described, using a mixed linear combination of atomic orbitals (LCAO)-point ion lattice scheme. An estimated transition energy of 4.7 eV and oscillator strength near unity is compared with various observed absorption peaks in the middle ultraviolet. Including estimated polarization and deformation corrections we give for the ${{\Gamma }_1}^e$ energy $E_0$, with respect to the vacuum, $E_0\lesssim -13.0\mathrm{}$ eV, i.e., below the presently assumed valence band maximum of about -9.5 eV. Implications of such a result, e.g., that the ${\mathrm{O}}^{2-}$ vacancy trap may not be bleachable by ionizing radiation, are discussed, especially with reference to mixed electron spin resonance (ESR)-optical experiments.