Distribution and topology of the electron density in an aluminosilicate compound from high-resolution x-ray diffraction data: the case of scolecite

The experimental electron density distribution in scolcite, CaAl2Si3O10.3H( 2)O, has been derived from single-crystal high-resolution Ag K alpha X-ray diffraction data. A statistical method based on the prediction matrix has b een used to discuss the estimation of the valence populations (P-val) in th e kappa least-squares refinements. The densities on the Si-O-Si and SiO-Al bridges have been characterized using the topology of the electron density through its Laplacian at the bond critical points. The Si-O and Al-O bond f eatures are related to the atomic environment and to the Si-O-T geometries (T = Si, Al).