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水中离子和极性分子的分子理论与模拟

Molecular theories and simulation of ions and polar molecules in water

Gerhard Hummer, Lawrence R. Pratt, Angel E. Garcia

备注：
invited J. Phys. Chem. feature article, 30 pages including 10 figures, minor stylistic revisions
发表信息：
J. Phys. Chem. A 102, 7885 (1998)
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摘要：

综述了近年来水溶液中离子和极性分子的分子理论和模拟研究进展。咪唑和咪唑盐溶质的水合作用被用来解释理论问题。远程静电相互作用在模拟的治疗进行了广泛的讨论。有人认为，埃瓦尔德的方法是一种简单的方法来获得正确的水合自由能的热力学极限从分子计算，和埃瓦尔德相互作用和周期性边界条件的分子模拟也可以比许多常见的替代品更有效。埃瓦尔德处理允许对无限系统大小进行结论性外推。从简单模型的测试中出现的画面是，最简单的理论最突出的失败与溶剂质子构象有关，导致静电势的非高斯波动。因此，对于二阶微扰理论最有利的情况是单原子正离子。对于极性和阴离子溶质，连续或高斯理论是不太准确的。对这些简单模型的具体缺陷的理解导致了新的概念，多态高斯和准化学理论，这些理论解决了简单理论失败的情况。有人认为，相对于直接介电连续处理，准化学理论提供了一个更好的理论组织的计算研究的溶液物种的电子结构。

英文摘要：

Recent developments in molecular theories and simulation of ions and polar molecules in water are reviewed. The hydration of imidazole and imidazolium solutes is used to exemplify the theoretical issues. The treatment of long-ranged electrostatic interactions in simulations is discussed extensively. It is argued that the Ewald approach is an easy way to get correct hydration free energies in the thermodynamic limit from molecular calculations; and that molecular simulations with Ewald interactions and periodic boundary conditions can also be more efficient than many common alternatives. The Ewald treatment permits a conclusive extrapolation to infinite system size. The picture that emerges from testing of simple models is that the most prominent failings of the simplest theories are associated with solvent proton conformations that lead to non-gaussian fluctuations of electrostatic potentials. Thus, the most favorable cases for the second-order perturbation theories are monoatomic positive ions. For polar and anionic solutes, continuum or gaussian theories are less accurate. The appreciation of the specific deficiencies of those simple models have led to new concepts, multistate gaussian and quasi-chemical theories, that address the cases for which the simpler theories fail. It is argued that, relative to direct dielectric continuum treatments, the quasi-chemical theories provide a better theoretical organization for the computational study of the electronic structure of solution species.

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