Yu Haibo, van Gunsteren Wilfred F
Laboratory of Physical Chemistry, Swiss Federal Institute of Technology Zurich, ETH Hönggerberg, 8093 Zürich, Switzerland.
J Chem Phys. 2004 Nov 15;121(19):9549-64. doi: 10.1063/1.1805516.
The properties of two improved versions of charge-on-spring (COS) polarizable water models (COS/G2 and COS/G3) that explicitly include nonadditive polarization effects are reported. In COS models, the polarization is represented via a self-consistently induced dipole moment consisting of a pair of separated charges. A previous polarizable water model (COS/B2), upon which the improved versions are based, was developed by Yu, Hansson, and van Gunsteren. To improve the COS/B2 model, which overestimated the dielectric permittivity, one additional virtual atomic site was used to reproduce the water monomer quadrupole moments besides the water monomer dipole moment in the gas phase. The molecular polarizability, residing on the virtual atomic site, and Lennard-Jones parameters for oxygen-oxygen interactions were varied to reproduce the experimental values for the heat of vaporization and the density of liquid water at room temperature and pressure. The improved models were used to study the properties of liquid water at various thermodynamic states as well as gaseous water clusters and ice. Overall, good agreement is obtained between simulated properties and those derived from experiments and ab initio calculations. The COS/G2 and COS/G3 models may serve as simple, classical, rigid, polarizable water models for the study of organic solutes and biopolymers. Due to its simplicity, COS type of polarization can straightforwardly be used to introduce explicit polarization into (bio)molecular force fields.
本文报道了电荷弹簧（COS）可极化水模型的两个改进版本（COS/G2和COS/G3）的性质，这两个模型明确包含了非加和极化效应。在COS模型中，极化通过由一对分离电荷组成的自洽诱导偶极矩来表示。之前的可极化水模型（COS/B2）是由Yu、Hansson和van Gunsteren开发的，改进版本就是基于此模型。为了改进高估介电常数的COS/B2模型，除了气相中的水单体偶极矩外，还使用了一个额外的虚拟原子位点来重现水单体四极矩。位于虚拟原子位点上的分子极化率以及氧-氧相互作用的 Lennard-Jones 参数被改变，以重现室温及压力下液态水的汽化热和密度的实验值。改进后的模型用于研究不同热力学状态下液态水以及气态水团簇和冰的性质。总体而言，模拟性质与实验和从头算计算得出的性质之间取得了良好的一致性。COS/G2和COS/G3模型可作为研究有机溶质和生物聚合物的简单、经典、刚性、可极化水模型。由于其简单性，COS类型的极化可直接用于将显式极化引入（生物）分子力场。
