https://orcid.org/0000-0001-5247-8514
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Abstract
A new method for Boundary Driven Non-Equilibrium Molecular Dynamics (BD-NEMD) simulation is presented. It allows the simultaneous imposition of both a constant temperature and concentration gradient. By varying the strength of the imposed gradients and obtaining stationary values of the mass and energy flux, this new technique can be used to extract the Onsager transport coefficients directly. We demonstrate the setup and measure explicitly the Soret and Dufour effects for a binary mixture of Argon and Krypton. We compare the Soret coefficient computed using this new scheme against the experimentally inspired protocol where the system has no mass current. However, this method is limited to only an estimate of the Soret coefficient rendered inefficient due to the poor signal-to-noise ratio and cannot give the transport coefficients explicitly. The new technique allows for accurate measurements of non-zero flux values and, if run in the linear response domain, the full set of transport coefficients can be extracted directly. We also speculate about how this scheme could be applied to more complex systems with applications for polymer separations and biological activities.
GRAPHICAL ABSTRACT
Acknowledgments
We are delighted to dedicate this small contribution in non-equilibrium molecular simulation to Mike Klein who has just achieved his 80 years. We wish he will continue to share with us his human and scientific wisdom for many years to come. This work is supported by grants from the Welch Foundation F-1896 and from the NIH GM059796.
Disclosure statement
No potential conflict of interest was reported by the author(s).