Self–diffusion of water molecules confined between quartz surfaces at elevated temperatures by molecular dynamics simulations

Abstract

Molecular dynamics (MD) simulations were performed to investigate the self–diffusion coefficients and density profiles of water confined between quartz (1010) surfaces at 298–573 K. The self–diffusion coefficient of water near the surface was lower than that of water far from the surface. The density profiles of H₂O molecules showed several layered structures near the surface. In the thickness of 4.8 nm of H₂O at 298 K, the thickness of layered structure was estimate to be 1.0 nm, and the self–diffusion coefficient was reduced in 1.0 nm distance from the surface. At 573 K, the thickness of reducing area could be larger than the thickness of layered structure of 1.5 nm. Even in higher temperature conditions such as 573 K, the self–diffusion coefficient of water near the surface was reduced.