A QUANTUM-MECHANICAL CALCULATION OF THE DYNAMIC STRUCTURE FACTORS OF MAGNESIUM DIFLUORIDE

摘要

Ab initio calculations of dynamic structure factors are performed with a methodology that requires the crystalline density matrix determined by the periodic Hartree-Fock CRYSTAL code. Amplitudes and orientations of the atomic vibrations are fixed by the mean-square displacements available in the literature. This method, which is here upgraded so as to satisfy normalization conditions, gives rise, for any temperature T, to a ''dynamic'' density matrix different from the static one. An application to the calculation of the dynamic structure factors of magnesium difluoride (MgF2), which has anisotropic mean-square displacement tensors, is proposed and compared with experiments at 298 K. (C) 1996 John Wiley & Sons, Inc. [References: 21]