Ab initio study of the hydroxylated surface of amorphous silica: A representative model

A new complete, representative model for the hydroxylated surface of amorphous silica is presented and characterized by means of periodic DFT calculations. This model accounts for the experimentally encountered ring size distribution, Si-O-Si and O-Si-O angles, silanols density, and distribution (isolated, associated, geminals). Properties such as NMR shifts, dehydrogenation energies, OH vibrational frequencies, and the interaction with water are investigated. The results are compared with former experimental and theoretical results. This new representative model for this complex surface would probably help the investigation of its reactivity toward amino acids or other organic molecules, opening new perspectives in the understanding of the chemistry of amorphous materials.