Optimizing Noble Gas鈥揥ater Interactions via Monte Carlo Simulations

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• 作者：Oliver Warr ; Chris J. Ballentine ; Junju Mu ; Andrew Masters
• 刊名：Journal of Physical Chemistry B
• 出版年：2015
• 出版时间：November 12, 2015
• 年：2015
• 卷：119
• 期：45
• 页码：14486-14495
• 全文大小：447K
• ISSN：1520-5207

文摘

In this work we present optimized noble gas鈥搘ater Lennard-Jones 6-12 pair potentials for each noble gas. Given the significantly different atomic nature of water and the noble gases, the standard Lorentz鈥揃erthelot mixing rules produce inaccurate unlike molecular interactions between these two species. Consequently, we find simulated Henry鈥檚 coefficients deviate significantly from their experimental counterparts for the investigated thermodynamic range (293鈥?53 K at 1 and 10 atm), due to a poor unlike potential well term (蔚_ij). Where 蔚_ij is too high or low, so too is the strength of the resultant noble gas鈥搘ater interaction. This observed inadequacy in using the Lorentz鈥揃erthelot mixing rules is countered in this work by scaling 蔚_ij for helium, neon, argon, and krypton by factors of 0.91, 0.8, 1.1, and 1.05, respectively, to reach a much improved agreement with experimental Henry鈥檚 coefficients. Due to the highly sensitive nature of the xenon 蔚_ij term, coupled with the reasonable agreement of the initial values, no scaling factor is applied for this noble gas. These resulting optimized pair potentials also accurately predict partitioning within a CO₂鈥揌₂O binary phase system as well as diffusion coefficients in ambient water. This further supports the quality of these interaction potentials. Consequently, they can now form a well-grounded basis for the future molecular modeling of multiphase geological systems.