Molecular dynamics simulation of nanoporous silica

The micro-structure and dynamical properties of nanoporous silica are investigated using the molecular dynamics simulation method. The porous silica obtained have densities down to 0.7 g/ml and a mass fractal dimension of 2.6 or higher. The specific surface of the porous silica is calculated and found to be in agreement with adsorption experiments. The vibrational and dielectric power spectra show an enhanced intensity in the low frequency region. The low frequency modes are characterised by a covariance matrix eigenvector analysis and found to correspond to cluster motion.