Peculiarities of the silica surface center structure in rigid dehydroxidation conditions

摘要

A model of molecular claster and nomempirical calculation schemes MP2/6-31G*, MP4/6-31G*, and MP2/DZVP2 were applied to study electronic and energy characteristics of the surface centers of different SiO2 modifications in rigid dehydroxidation conditions. It was established that depending on an angle alpha = Si'O'Si" (where O' is an oxygen atom of the nearest to the surface layer), O* atom corresponding with two surface Si atoms, could (i) form a chemical bond with one of the Si' or Si"-centers (an asymmetric configuration, alpha > 118 divided by 120); or (ii) be common for these centers (a symmetric configuration, alpha < 118 divided by 120). It was also established that when alpha > 132 divided by 133, the basic state was triple and at alpha < 132 divided by 133, it was single. (c) 2006 Wiley Periodicals, Inc.