Department of Chemistry, University of Zurich, Zurich, Switzerland.
Department of Chemistry, University of Basel, Basel, Switzerland.
J Chem Phys. 2018 Jun 28;148(24):244504. doi: 10.1063/1.5037062.
A polarizable water model is presented which has been calibrated against experimental THz and Raman spectra of bulk water. These low-frequency spectra directly probe the dynamics, and thereby intermolecular interactions, on time scales relevant to molecular motions. The model is based on the TL4P force field developed recently by Tavan and co-workers [J. Phys. Chem. B 117, 9486 (2013)], which has been designed to be transferable between different environments; in particular, to correctly describe the electrostatic properties of both the isolated water molecule in the gas-phase and the liquid water at ambient conditions. Following this design philosophy, TL4P was amended with charge transfer across hydrogen-bonded dimers as well as an anisotropic polarizability in order to correctly reproduce the THz and Raman spectra. The thermodynamic and structural properties of the new model are of equal quality as those of TL4P, and at the same time, an almost quantitative agreement with the spectroscopic data could be achieved. Since TL4P is a rigid model with a single polarizable site, it is computationally very efficient, while the numerical overhead for the addition of charge transfer and the anisotropic polarizability is minor. Overall, the model is expected to be well suited for, e.g., large scale simulations of 2D-Raman-THz spectra or biomolecular simulations.
本文提出了一种可极化水模型，该模型通过与体相水的太赫兹（THz）和拉曼（Raman）光谱实验进行校准。这些低频光谱直接探测动力学，从而探测与分子运动相关的时间尺度上的分子间相互作用。该模型基于最近由 Tavan 及其同事开发的 TL4P 力场[J. Phys. Chem. B 117, 9486 (2013)]，旨在不同环境之间具有可转移性；特别是，正确描述气相中孤立水分子和环境条件下水的液体的静电性质。遵循这一设计理念，TL4P 经过修订，增加了氢键二聚体之间的电荷转移以及各向异性极化率，以正确再现 THz 和拉曼光谱。新模型的热力学和结构性质与 TL4P 相当，同时，几乎可以与光谱数据完全吻合。由于 TL4P 是一个具有单个可极化位点的刚性模型，因此计算效率非常高，而添加电荷转移和各向异性极化率的数值开销很小。总的来说，该模型有望非常适合大规模的二维 Raman-THz 光谱模拟或生物分子模拟等应用。
