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Transferable Anisotropic United-Atom Mie (TAMie) Force Field: Transport Properties from Equilibrium Molecular Dynamic Simulations

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journal contribution
posted on 27.04.2020, 12:14 by Matthias Fischer, Gernot Bauer, Joachim Gross
Reliable prediction of transport coefficients for fluids, such as the viscosity, thermal conductivity, and diffusion coefficients, is an important prerequisite for process design. Besides experimental measurements and semiempirical correlations, molecular simulations are a promising method to estimate transport properties of fluids over wide ranges of temperatures and pressures. Transport properties are sensitive to the underlying intermolecular potentials. In this work we assess the Transferable Anisotropic united-atom Mie (TAMie) force field regarding the calculation of transport properties. The force field was parametrized for thermodynamic properties with emphasis on vapor–liquid coexistence properties. Equilibrium molecular dynamic simulations are used to calculate all transport properties in a single simulation, using the corresponding Green–Kubo methods. The simulated state points were distributed in the temperature and pressure based on an entropy scaling approach, where the PC-SAFT equation of state is used to calculate residual entropy. Utilizing the favorable behavior of dynamic properties when plotted over the residual entropy, only few simulations are needed to parametrize a correlation function that furthermore enables comparison with experimental data over a wide range of temperatures and pressures. TAMie yields good results for all transport properties and substances investigated (with average absolute deviations of 13% for viscosity, 18% for diffusion, and 10% for thermal conductivity), given that only static properties were considered in the parametrization of the force field. Combining few simulations with the entropy scaling method enables very efficient prediction of transport properties for a large temperature and pressure region.