Electronic structure of sodium silicate glasses

Abstract

We have calculated the electronic structure of (Na 2 O) x (SiO 2 ) 1 − x glasses with x values of 0. 0.018. 0.111, 0.222, and 0.333 on atomic models with periodic boundary conditions. The calculations were performed using the first-principles, orbital-charge self-consistent orthogonalized linear combination of the atomic Orbitals method. Density of states, partial density of states, localization of the one-electron states, and effective valence charges were calculated for this system. These are compared with experimental results from the literature. Systematic correlations between the calculated electronic structure and the short-range atomic structure are presented. It is also shown that the states at the edges of the valence band become much more localized as Na is added to the system. This is mainly attributed to a decrease in the number of covalent bonds at the oxygen sites.