Distribution and Topology of the Electron Density in an Aluminosilicate Compound from High-Resolution X-ray Diffraction Data: the Case of Scolecite

Abstract

The experimental electron density distribution in scolecite, CaAl2Si3O10.3H2O, has been derived from single-crystal high-resolution Ag Kα X-ray diffraction data. A statistical method based on the prediction matrix has been used to discuss the estimation of the valence populations (P val) in the kappa least-squares refinements. The densities on the Si—O—Si and Si—O—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 features are related to the atomic environment and to the Si—O—T geometries (T = Si, Al).