Boundary-Driven Non-Equilibrium Molecular Dynamics Calculation of the Soret Coefficient in n-Hexane/n-Dodecane Mixtures

The Soret coefficients of n-hexane/n-dodecane mixtures were calculated by the enhanced heat exchange (eHEX) algorithm with the TraPPE-UA force field. The time that the system takes to reach the steady state has been investigated, the system is easier to reach thermal steady state than concentration steady state and composition is not a simulation time affecting factor in a fixed molecule number system. The Soret coefficients calculated in this work are in good agreement with experimental data from literatures, and the differences between the two means are no more than 12%. The variation tendency of the Soret coefficients is going up after dropping with increasing molar fraction of n-C-12 in the mixture, and the minimum value can be obtained at x(1) = 0.7. The coincidence of the simulated and experimental data affirms the availability of TraPPE-UA force field applied in transport simulation and the validity of eHEX algorithm used in NEMD processes.