Behavior of Atoms at the Surface of a K₂O · 3siO₂ Glass—A Molecular Dynamics Simulation

Recent ion scattering spectroscopy (ISS) studies indicate that an excess of K ions occurs at the surface of a K₂O · 3SiO₂ glass. Molecular dynamics (MD) computer simulations were used to evaluate the short‐time dynamic behavior of atoms at the surface of such a glass in order to determine a mechanism for the K ion enrichment. In the simulations, a bulk glass of several hundred atoms was melted using three‐dimensional periodic boundary conditions, and subsequently quenched to lower temperatures. Periodic boundary conditions were removed in one dimension near room temperature so as to create free surfaces. The distribution of species perpendicular to the free surface was determined. The MD simulations show that K ions can build up at the outermost surface of the glass within several picoseconds after formation of the surface.