New Directions in the Study of Ice and Water Clusters

俄亥俄州立大学的Sherwin Singer在理论和计算化学项目的支持下，研究了广泛的水系统，从小的水簇到大的水和冰，使用分析和数值理论方法。本研究的一个统一主线是根据氢键网络的拓扑结构对水结构进行分析。在只有数值模拟才可行的情况下，使用氢键拓扑可以得到系统的分析结果。此外，分析方法允许从小水团或冰单元中提取氢键性质，并以非常普遍的方式将这些参数应用于足够大的系统进行统计模拟。这样，小系统的高水平从头计算的结果可以推广到预测热力学极限下的统计性质。统计模拟也将用经验电位进行，包括PI自己的解离水模型。其他计划包括用从头算研究检查经验势的性能，振动运动的量子蒙特卡罗研究，以及开发新的从头算分子动力学方法。模拟生物分子、大气化学系统或地下水中的污染物的行为需要精确的液态水、冰和水团模型。现有的液态水模型需要改进，这将从本研究的结果中得出。

Sherwin Singer of the Ohio State University is supported by the Theoretical and Computational Chemistry Program to study a wide range of aqueous systems, from small water clusters to bulk water and ice, using both analytical and numerical theoretical methods. One unifying thread in this research is the analysis of water structures in terms of the topology of the hydrogen bond network. Working with the hydrogen bond topology yields analytical results for systems where only numerical simulations would seem feasible. Moreover, the analytical approach allows extraction of hydrogen bonding properties from small water clusters or ice unit cells and, in a very general fashion, application of these parameters to systems large enough for statistical simulations. In this way, the results of high level ab initio calculations on small systems can be extended to predict statistical properties in the thermodynamic limit. Statistical simulations will also be performed with empirical potentials, including the PI's own dissociating water model. Other plans include checks on the performance of empirical potentials with ab initio studies, quantum Monte Carlo studies of vibrational motion, and development of new ab initio molecular dynamics methods.Modeling the behavior of biological molecules, systems in atmospheric chemistry, or pollutants in the ground water requires accurate models for liquid water, ice, and water clusters. The models for liquid water that exist are in need of improvements, which will result from the outcomes of this research.