Development of EEM based silicon-water and silica-water wall potentials for non-reactive molecular dynamics simulations

Molecular dynamics simulations of heat transfer in gases are computationally expensive when the wall molecules are explicitly modeled. To save computational time, an implicit boundary function is often used. Steele's potential has been used in studies of fluid-solid interface for a long time. In this work, the conceptual idea of Steele's potential was extended in order to simulate water-silicon and water-silica interfaces. A new wall potential model is developed by using the electronegativity-equalization method (EEM), a ReaxFF empirical force field and a non-reactive molecular dynamics package PumMa. Contact angle simulations were performed in order to validate the wall potential model. Contact angle simulations with the resulting tabulated wall potentials gave a silicon-water contact angle of 129°, a quartz-water contact angle of 0°, and a cristobalite-water contact angle of 40°, which is in reasonable agreement with experimental values.