Shell model calculations of the energies of formation of point defects in alkaline earth fluorides

The authors have obtained shell model potentials for CaF 2 , SrF 2 and BaF 2 by fitting models to macroscopic data for these crystals; improved fits have been obtained only by the inclusion in the potential of attractive second neighbour interactions that are much stronger than the normal Van der Waals forces. They have used the potentials to calculate point defect formation and migration energies in these crystals, using the HADES program.