An exploratory examination of the electron density and electrostatic potential of phenakite

The deformation electron density and total electrostatic potential of phenakite, Be₂SiO₄, are retrieved from single-crystal X-ray diffraction intensities. Refinements are completed using several models, including a flexible pseudoatom model wherein the electron density about each nucleus is represented by a short multipole expansion. Associated with each nearest-neighbor Be-O and Si-O interatomic vector is an accumulation of deformation density. Short bonds have greater deformation-density accumulation than do long bonds between similar atoms. The topography of the deformation density about each oxygen indicates, in a qualitative sense, both ionic and covalent contributions to the bonding.