Multipole-refined charge density study of diopside at ambient conditions

The experimental multipole electron density, Rò(r), of diopside was derived from high-resolution single-crystal diffraction at room temperature. Its topological analysis revealed predominantly ionic Si–O bonding, as found in electron density studies of other silicates. In particular, the non-bridging Si–O bonds are slightly less ionic in character than the bridging Si–O bonds. The Ca–O and Mg–O bonds are classified as pure closed-shell ionic interactions.All these results were also confirmed by periodic restricted Hartree–Fock (RHF) calculations.