Non-equilibrium molecular dynamics simulation as a method of calculating thermodynamic coefficients

A method is proposed in the present study, by which the specific heat at constant pressure, c_p, and the thermal expansion coefficient, α_p, at different temperatures along an isobar can be derived from a single run of non-equilibrium molecular dynamics (NEMD) at using a steady temperature gradient. This study aims to demonstrate the method and examine its validity in the NEMD simulation. For Lennard-Jones fluids, it is shown that the c_p and α_p obtained from the NEMD simulations are in good agreement with those calculated in a traditional manner from the equilibrium fluctuations. The results of the present study suggest that a NEMD simulation with heat conduction is useful not only to measure thermal conductivity but also to determine these thermodynamic coefficients. In particular, there is a possibility that the present method is applicable even to heterogeneous systems, to which the standard method is difficult to apply.