Electronic structure and oxygen bonding in CaSiO3 silicate

Bonding of the bridging oxygen (BO) and non-bridging oxygen (NBO) sites in the CaSiO3 silicate is studied using soft x-ray emission, absorption and electron energy-loss spectroscopy of the oxygen K edge. Comparisons with APW + lo calculations are discussed, showing that this method can be applied successfully to silicates, which have large unit cells. Several specific features due to BO and NBO atoms in the density of states are reproduced by the calculations. The bonding in CaSiO3 is also examined using electron density maps. Our analysis of deformation electron density maps supports the idea that the NBO to Si bond is more ionic than the BO to Si bond.