On the condensation mechanism of the dioxides of sixth- group elements: an ab initio approach

摘要

A quantum mechanical ab initio simulation of XO2 molecules (X = O, S, Se, Te and Po) and the relevant dimers has been performed. The X - O bond polarity and the bent configuration of the XO2 species are discussed as factors governing their condensation mechanisms. Three points are emphasized: (i) the fundamental difference between the constitution of the condensed phases of OO2 and SO2, on the one hand, and those of SeO2 and TeO2, on the other; (ii) the occurrence of polymorphism in crystalline TeO2 and its absence in crystalline SeO2; (iii) the driving forces of the gamma-alpha polymorph transformation in crystalline TeO2.