Programme

P.4 -- Poster, VCTP-44

Date: Tuesday, 30 July 2019

Time: 08:30 - 10:00

Self-Diffusion Coefficient of Solute Molecule in Diluted Mixtures: A Non-Equilibrium Molecular Dynamics Approach

Quang Quoc Viet Thieu (1), Hai Hoang (2), Julien Collell (3), Magali Pujol (3), Guillaume Galliero (4),*

(1) Can Tho University, Campus II, 3-2 Street, Ninh Kieu District, Can Tho City 94000, Viet Nam; (2) Institute of Fundamental and Applied Sciences, Duy Tan University, 10C Tran Nhat Duat Street, District 1, Ho Chi Minh City 700000, Viet Nam; (3) TOTAL S.A., CSTJF, Avenue Larribau, Pau, 64018, France; (4) Laboratoire des Fluides Complexes et leurs Réservoirs (UMR-5150 with CNRS, and TOTAL), Université de Pau et des Pays de l’Adour, BP 1155, F-64013 Pau Cedex, France.

Accurate estimates of self-diffusion coefficient of solute molecule at infinite dilution in mixtures plays a key role in many fields, in particular in geological and petroleum engineering. Molecular dynamics simulations have become a powerful tool to predict thermophysical properties of fluids including the self-diffusion coefficient. This quantity is often computed by performing equilibrium MD (EMD) simulations using classical algorithms such as Green-Kubo or Einstein relations. However, when dealing with an infinitely diluted mixture these relations are difficult to apply because of the poor statistics, and so may lead to very large error bars. Thus, an efficient algorithm to calculate this property in MD simulations is highly desired. In this work, we have employed the Thermodynamic of Irreversible Process (TIP) formalism combined with the Einstein’s relation to propose an efficient algorithm used in MD simulations for the estimation of self-diffusion coefficient of solute molecule at infinite dilution. The algorithm consists in applying an external force on the solute molecule, and computing its steady velocity, i.e. carrying out Non-equilibrium MD (NEMD) simulations. As an application of the method we have studied the self-diffusion coefficients of noble gases in bulk water and saturated clay to check the accuracy of mass square-root relation.

Presenter: Thieu Quang Quoc Viet