Communication: A method to compute the transport coefficient of pure fluids diffusing through planar interfaces from...

Area of Science:

• Computational physics
• Chemical engineering
• Materials science

Background:

• Molecular dynamics simulations are key for diffusion coefficient computation.
• Classical methods fail for diffusion through thin interfaces due to ill-defined volumes.
• Non-equilibrium methods compute transport coefficients but cannot isolate mechanisms.

Purpose of the Study:

• To develop a simple and accurate method for computing diffusional transport coefficients through planar interfaces using equilibrium molecular dynamics.
• To calculate the diffusion coefficient per unit interface width for pure fluids.
• To offer a complementary technique for interpreting results from single-layer membranes.

Main Methods:

• Utilizing equilibrium molecular dynamics simulations.
• Developing a novel approach to define and compute the diffusion coefficient per unit interface width.
• Applying the method to a dilute gas diffusing through a porous solid interface.

Main Results:

• A new, accurate method for calculating diffusion coefficients across interfaces from equilibrium simulations was established.
• The method successfully computed the diffusional transport coefficient per unit interface width.
• Validation was performed using a case study of gas diffusion through a porous solid.

Conclusions:

• The proposed method accurately computes the diffusional transport coefficient per unit interface width from equilibrium molecular dynamics.
• This technique offers a valuable alternative to complex non-equilibrium methods for studying single-layer membranes.
• The approach enhances the understanding of fluid diffusion across interfaces in molecular systems.