期刊
JOURNAL OF CHEMICAL PHYSICS
卷 140, 期 17, 页码 -出版社
AMER INST PHYSICS
DOI: 10.1063/1.4871873
关键词
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资金
- Office of Science of the U.S. Department of Energy (DOE) [DEAC05-00OR22725]
- Engineering and Physical Sciences Research Council [EP/K038249/1]
- European Research Council
- Royal Society through a Royal Society Wolfson Research Merit Award
- EPSRC [EP/K038249/1, EP/I030131/1] Funding Source: UKRI
- Engineering and Physical Sciences Research Council [EP/K038249/1, EP/I030131/1] Funding Source: researchfish
High quality reference data from diffusion Monte Carlo calculations are presented for bulk sI methane hydrate, a complex crystal exhibiting both hydrogen-bond and dispersion dominated interactions. The performance of some commonly used exchange-correlation functionals and all-atom point charge force fields is evaluated. Our results show that none of the exchange-correlation functionals tested are sufficient to describe both the energetics and the structure of methane hydrate accurately, while the point charge force fields perform badly in their description of the cohesive energy but fair well for the dissociation energetics. By comparing to ice I-h, we show that a good prediction of the volume and cohesive energies for the hydrate relies primarily on an accurate description of the hydrogen bonded water framework, but that to correctly predict stability of the hydrate with respect to dissociation to ice Ih and methane gas, accuracy in the water-methane interaction is also required. Our results highlight the difficulty that density functional theory faces in describing both the hydrogen bonded water framework and the dispersion bound methane. (C) 2014 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.
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