COMPUTATIONAL MODELING OF AMORPHOUS SILICA .1. MODELING THE STARTING STRUCTURES - A GENERAL CONCEPTION

This paper presents concepts underlying computational modeling of disp ersive silicas. An object for modeling is polyatomic nanometer-sized c lusters. A chemical software package adapted for the PC AT 386(486)/38 7 is utilized. A structure-sensitive method of vibration spectroscopy is suggested to verify the results. Ultradispersive materials are cons idered to be an adequate object to establish feedback between computat ional and real experiments. The program is realized on a set of disper sive silicas; an algorithm for construction of large clusters is propo sed, which is based on the concept of radical difference of dispersive silicas. From analysis of vibration spectra we suggest that aerosils, silica gels, and aerogels should be regarded as amorphous tecto-, cyc lo-, and polysilicas, respectively, in line with Liebau's classificati on of crystal silicates. The category of silica is determined by its p roduction procedure.