STRUCTURAL CORRELATIONS IN POROUS SILICA - MOLECULAR-DYNAMICS SIMULATION ON A PARALLEL COMPUTER

Molecular dynamics simulations of porous silica in the density range 2.2-0.1 g/cm3 are carried out on a 41 472 particle system using a multiple instruction multiple data computer. The internal surface area, pore surface-to-volume ratio, pore size distribution fractal dimension, correlation length, and mean particle size are determined as a function of the density. Structural transition between a condensed amorphous phase and a low-density porous phase is characterized by these quantities. Various dissimilar porous structures with different fractal dimensions are obtained by controlling the preparation schedule and temperature.