Theoretical study of the polymer molecules (TeO2) as model systems for the local structure in TeO2 glass

Stable (TeO 2 ) n polymers (n < 7) in the form of chains, rings and three-dimensional entities are studied through the ab initio B3LYP calculations including their Raman spectra, polarizabilities and hyperpolarizabilities. The 3D-polymers are found to be the most stable, and can be proposed as the model fragments of TeO 2 glass. According to the calculations, the huge hyperpolarizability of TeO 2 -based compounds is likely to be related to the essentially delocalized electron states (inherent to polymerized systems), and not to the electron lone pairs of tellurium atoms.