Molecular dynamics simulation of helium diffusion in vitreous silica

• The diffusion was simulated without any a priory data on the structure of matrix.
• The prepared model of vitreous silica has the correct volume of interstitial voids.
• The calculated diffusion coefficients of helium are close to experimental values.

The helium diffusion through the non-porous vitreous silica was simulated by the molecular dynamics (MD) method. Truncated Morse potential was used to create models of vitreous silica. It was found that the quality of the simulation has been determined by the two main factors: the correct model of matrix in terms of the interstitial space geometry, and the quality of the gas-matrix interaction potential parameterization. The density of silica glass was in a good accordance with the experimental value 2.2 g/cm3. The helium-silica interaction potential's parameterization has been done as close as possible to the conditions of a real migration of helium through the doorways connecting adjacent solubility sites. Taking into account of these two factors has allowed simulating the diffusion of helium through vitreous silica by molecular dynamics simulation quantitatively and calculating the diffusion coefficients which are close to the experimental values available in the literature.