Benchmarking the performance of density functional theory and point charge force fields in their description of sI methane hydrate against diffusion Monte Carlo
Benchmarking the performance of density functional theory and point charge force fields in their description of sI methane hydrate against diffusion Monte Carlo
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DOI：
10.1063/1.4871873
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发表时间：
2014-05-07
影响因子：
4.4
通讯作者：
Michaelides, Angelos
中科院分区：
文献类型：
--
作者：
Cox, Stephen J.;Towler, Michael D.;Michaelides, Angelos
高质量的参考数据，从扩散蒙特卡罗计算散装SI甲烷水合物，复杂的晶体表现出氢键和分散为主的相互作用。评价了几种常用的交换关联泛函和全原子点电荷力场的性能。我们的研究结果表明，没有一个测试的交换相关泛函是足够的能量和结构的甲烷水合物准确地描述，而点电荷力场表现不佳，在他们的描述的结合能，但公平以及解离能量。通过与冰I-h的比较，我们表明，对水合物的体积和内聚能的良好预测主要依赖于对氢键水框架的准确描述，但为了正确预测水合物相对于解离的稳定性冰I-h和甲烷气体，还需要水-甲烷相互作用的准确性。我们的研究结果突出了密度泛函理论在描述氢键水框架和分散束缚甲烷时所面临的困难。(C)2014年作者。所有文章内容，除非另有说明，是根据知识共享署名3.0未移植许可证许可。
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.