Abstract: | Quantum Chemical Model Calculations on the Migration of Si? F Groups in Hexafluorosilicates The transport of different Si? F species was simulated using two SiF6]2? octahedra as example. Activation barriers and charge distributions were calculated with the EHT method. Bearing in mind the structure of cubic hexafluorosilicates calculations were carried out on the migration both along an edge and along a (110) face of the elementary cell. At first SiF2]2+ and SiF4 groups were removed from an Si2F12]4? unit to produce a surface vacancy. During a second step planar SiF4 groups were moved to the neighbouring lattice position. A diffusion of planar SiF4 is favoured, if the electrostatic interaction between moved and fixed fluorine atoms is as small as possible. |