UBC Theses and Dissertations
An M.O. study of the stereochemistry and energy of three-repeat single silicate chains Roussy, Marie Monique
Hypothetical three—repeat single chains consisting of regular SiO₄ tetrahedra were generated with a computer program to study the possible conformations and their total potential energy by the CNDO/2 molecular orbital method. Calculations were restricted to those chains with ⌊Si-O-Si between 110° and 180° with an average of 140° and ⌊(O-O-O)[sub=br] between 90° and 180°. In addition, successive pairs of tetrahedra in each chain were restricted to either single or double—eclipsed or staggered conformation. Those chains with the largest d(Si—Si) and at least one staggered pair of tetrahedra have a lower energy. These are not, as yet, observed in nature presumably because their packing does not accomodate the interstial cations.
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