Theoretical ab initio calculations of the structure factors of fluorite (CaF₂)

Ab initio calculations of static structure factors of fluorite (CaF₂) are performed by a linear combination of atomic orbitals Hartree-Fock method as implemented in the CRYSTAL program. The effect of thermal motion is then introduced by taking into account the atomic mean square displacements given in the literature at different temperatures and leads to dynamic structure factors. Finally, a very slight displacement of fluorine ions with respect to their ideal position is considered, to simulate an anharmonic vibration or disordered structure so as to improve the agreement with experimental data.