Gaussian-Charge Polarizable and Nonpolarizable Models for CO2

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• 作者：Hao Jiang ; Othonas A. Moultos ; Ioannis G. Economou ; Athanassios Z. Panagiotopoulos
• 刊名：Journal of Physical Chemistry B
• 出版年：2016
• 出版时间：February 11, 2016
• 年：2016
• 卷：120
• 期：5
• 页码：984-994
• 全文大小：505K
• ISSN：1520-5207

文摘

A polarizable intermolecular potential model using three classical Drude oscillators on the atomic sites has been developed for CO₂. The model is rigid with bond lengths and molecular geometries set to their experimental values. Electrostatic interactions are represented by three Gaussian charges connected to the molecular frame by harmonic springs. Nonelectrostatic interactions are represented by the Buckingham exponential-6 potential, with potential parameters optimized to vapor–liquid equilibria (VLE) data. A nonpolarizable CO₂ model that shares the other ingredients of the polarizable model was also developed and optimized to VLE data. Gibbs ensemble Monte Carlo and molecular dynamics simulations were used to evaluate the two models with respect to a variety of thermodynamic and transport properties, including the enthalpy of vaporization, second virial coefficient, density in the one-phase fluid region, isobaric and isochoric heat capacities, radial distribution functions, self-diffusion coefficient, and shear viscosity. Excellent agreement between model predictions and experimental data was found for all properties studied. The polarizable and nonpolarizable models provide a similar representation of CO₂ properties, which indicates that the properties of pure CO₂ fluid are not strongly affected by polarization. The polarizable model, which has an order of magnitude higher computational cost than the nonpolarizable model, will likely be useful for the study of a mixture of CO₂ and polar components for which polarization is important.