Ab Initio Molecular Dynamics Study of Heterogeneity at Amorphous Silica/Water Interface

We study the surface heterogeneity of the amorphous silica/water interface by ab initio molecular dynamics simulations. The structure of bulk amorphous silica produced by thermal annealing and the silanol (Si-OH) density at the silica surface reproduce the experiment. The angular probability distribution of silanol OH groups along the surface normal direction is quite broad, and the computed pKa strongly depends on the silanol species. All computed properties show large heterogeneity of the interface.