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Molecular Dynamics Simulation of Transport and Structural Properties of CO2 Using Different Molecular Models

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posted on 13.08.2015, 00:00 by Haimin Zhong, Shuhui Lai, Jinyang Wang, Wenda Qiu, Hans-Dietrich Lüdemann, Liuping Chen
The diffusion coefficients (Ds), viscosities (η), and structural properties of carbon dioxide (CO2) have been studied using molecular dynamics (MD) simulation. Three fully flexible models (MSM-flex, EPM2-flex, and TraPPE-flex) from the literature are used to model CO2. Present simulations have extended the temperature range from 223 K to 450 K and pressures up to 200 MPa for the first time. Generally, the simulation results show a good agreement with the experimental ones. The overall satisfaction of the EPM2-flex model is found to be the best, with an average absolute relative deviation of 6.83 % for Ds and of 2.87 % for η, respectively. However, the TraPPE-flex model performs best at low temperatures below 273 K. Meanwhile, the lifetime of CO2 molecules in the first solvation shell (τs) is calculated, and the qualitative correlation between τs and Ds as well as τs and η is discussed. Finally, the structures of CO2 fluid in different thermodynamic states are investigated by calculating radial distribution functions and using a clustering algorithm.

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