Особенности строения и перегруппировок поверхностных центров различных модификаций диоксида кремния в условиях жесткого дегидроксидирования

Within the framework of the model of molecular cluster the stable surface configurations of dehydroxidated silica were calculated at fixed values of an angle α =SiOSi responding to various SiO2 modifications, a non-empirical method MO LKAO in 6-31 G* basis being used. It was shown that the surface O* atom adjoined to one of Si atoms going out on a surface. It's equidistant from neighbouring Si atoms position (a tetranonial surface cycle) is transitional between the corresponding stable configurations. At angles α > 132° transition of O* from one center to another is hampered (a high energy barrier), at α > 123° ÷ 126° the barrier becomes insignificant (i. e. comparable with an energy of thermal movement) and such transition becomes possible (a relevant surface configuration may be considered as structurally not rigid).