Representability problems for coarse-grained water potentials
Representability problems for coarse-grained water potentials
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DOI：
10.1063/1.2715953
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发表时间：
2007-04-14
影响因子：
4.4
通讯作者：
Louis, Ard A.
中科院分区：
文献类型：
--
作者：
Johnson, Margaret E.;Head-Gordon, Teresa;Louis, Ard A.
有效分子间势的使用通常涉及更精确、复杂的函数形式和更易处理的简单表示之间的折衷。为了详细研究这种选择，我们系统地推导了粗粒度的各向同性对势，它精确地再现了TIP 4P-Ew水模型在密度范围从0.88到1.30 g/cm（3）和温度范围从235到310 K的状态点处的氧-氧径向分布函数。虽然通过构造这些有效势正确地代表了TIP 4P-Ew水的等温压缩性，但它们不能准确地解决其他热力学性质，如维里压力，内能或热力学异常。因为在一个给定的状态点的对电位，再现对结构是唯一的，因此，我们已经明确表明，它是不可能同时表示的对结构和几个关键的平衡水的热力学性质与状态点依赖的径向对称对电位。我们认为，这种代表性的问题是相关的，但不同的，更广泛地承认的可转移性问题，并详细讨论了这对水和其他液体的建模的影响，粗粒度的潜力。然而，不管热力学的不一致性，状态点相关的有效电位水不产生结构和动力学异常。(c)2007年，美国物理学会。
The use of an effective intermolecular potential often involves a compromise between more accurate, complex functional forms and more tractable simple representations. To study this choice in detail, we systematically derive coarse-grained isotropic pair potentials that accurately reproduce the oxygen-oxygen radial distribution function of the TIP4P-Ew water model at state points over density ranges from 0.88 to 1.30 g/cm(3) and temperature ranges from 235 to 310 K. Although by construction these effective potentials correctly represent the isothermal compressibility of TIP4P-Ew water, they do not accurately resolve other thermodynamic properties such as the virial pressure, the internal energy, or thermodynamic anomalies. Because at a given state point the pair potential that reproduces the pair structure is unique, we have therefore explicitly demonstrated that it is impossible to simultaneously represent the pair structure and several key equilibrium thermodynamic properties of water with state-point dependent radially symmetric pair potentials. We argue that such representability problems are related to, but different from, more widely acknowledged transferability problems and discuss in detail the implications this has for the modeling of water and other liquids by coarse-grained potentials. Nevertheless, regardless of thermodynamic inconsistencies, the state-point dependent effective potentials for water do generate structural and dynamical anomalies. (c) 2007 American Institute of Physics.