An investigation into the effects of ion incorporation on the electronic structure of silicate fragments via ab initio computational techniques

We investigate the changes in both the geometry and electronic structure of silicate fragments in response to the pressure of cations. In particular we focus on the double 4 ring, where the encapsulation of a F− anion, produces a transfer of appreciable electron density from the anion onto the framework silicon atoms, while on inclusion of a Na+ cation, electron density is transferred from the framework species onto the cation. Analysis of the Mulliken populations has identified that the Si atoms act as electron density sinks for such electron density transfer. Hydroxyl groups perturb the framework in a way which depends on the orientation of the hydroxyl molecule.