Electronic structure of the F centre in a sodium fluoride crystal

Abstract

A first-principle self-consistent-field calculation for the electronic structure of the F centre in a sodium fluoride crystal has been performed using the method of linear combinations of atomic orbitals in the Hartree-Fock-Slater framework. The interaction between the F-centre electron and all the ions in the crystal is fully taken into account to obtain the one-electron Hamiltonian. The F centre electronic wavefunctions are expanded as linear combinations of atomic and Gaussian orbitals at the vacant site and atomic sites through to the sixth or the seventh nearest neighbours. All the multicentre integrals in the matrix elements are evaluated exactly by means of the Gaussian technique. The calculated values of the ground-state wavefunction at the Na (1/200) and F (1/21/20) sites agree well with the experimental values derived from the observed hyperfine structure of the electron paramagnetic resonance spectrum. The calculated Gamma 1+- Gamma 4- absorption energy is also in good agreement with experiment.