Quantum-mechanical calculation of binding energy in fluorides with fluorite structure

According to the Lowdin method quantum-mechanical calculations of binding energy, unit cell parameter and volumetric compressibility in CaF2 and SrF2 crystals have been carried out. The calculation is made for several values of interionic distance in three different approximations. Comparison with experimental data has shown that the model is applicable for the description of interatomic interactions in fluorides with fluorite-type structure. The best agreement is achieved when two- and three-particle interactions in the first coordination sphere are taken into account