Biswas Rajib, Tse Ying-Lung Steve, Tokmakoff Andrei, Voth Gregory A
Department of Chemistry, James Franck Institute, and Institute for Biophysical Dynamics, The University of Chicago , Chicago, Illinois 60637, United States.
J Phys Chem B. 2016 Mar 3;120(8):1793-804. doi: 10.1021/acs.jpcb.5b09466. Epub 2015 Dec 1.
Results from condensed phase ab initio molecular dynamics (AIMD) simulations suggest a proton transfer reaction is facilitated by "presolvation" in which the hydronium is transiently solvated by four water molecules, similar to the typical solvation structure of water, by accepting a weak hydrogen bond from the fourth water molecule. A new version 3.2 multistate empirical valence bond (MS-EVB 3.2) model for the hydrated excess proton incorporating this presolvation behavior is therefore developed. The classical MS-EVB simulations show similar structural properties as those of the previous model but with significantly improved diffusive behavior. The inclusion of nuclear quantum effects in the MS-EVB also provides an even better description of the proton diffusion rate. To quantify the influence of anharmonicity, a second model (aMS-EVB 3.2) is developed using the anharmonic aSPC/Fw water model, which provides similar structural properties but improved spectroscopic responses at high frequencies.
凝聚相从头算分子动力学（AIMD）模拟结果表明，质子转移反应因“预溶剂化”而得到促进，其中水合氢离子通过接受来自第四个水分子的弱氢键，被四个水分子瞬时溶剂化，类似于水的典型溶剂化结构。因此，开发了一种纳入这种预溶剂化行为的新版本3.2多态经验价键（MS-EVB 3.2）水合过量质子模型。经典的MS-EVB模拟显示出与先前模型相似的结构性质，但扩散行为有显著改善。在MS-EVB中纳入核量子效应，也能更好地描述质子扩散速率。为了量化非谐性的影响，使用非谐aSPC/Fw水模型开发了第二个模型（aMS-EVB 3.2），该模型提供了相似的结构性质，但在高频下具有改进的光谱响应。
