Water has been widely studied because it plays a fundamental role in life on earth and is an active participant in many physical, chemical, and biological processes. Modeling water in condensed phases is an indispensable part of modern water research and rigid non-polarizable water models, such as TIP4P/2005, have been very popular in molecular simulations due to their high efficiency. Although these water models can reproduce many properties of water, they fail in predicting the dielectric properties of water, such as the dielectric constant. We propose to improve these models by modifying their dipole moment surfaces based on quantum chemistry calculations. Here, we propose a protocol that can assign partial atomic charges of water molecules in condensed phases properly. This protocol is devised based on benchmarking extensive quantum chemical calculations using various electronic-structure methods, basis sets, and population analysis methods against the properties of an isolated water molecule, water clusters, and liquid water. Good agreement is achieved between available experimental data and the calculated results based on our charge-assigning protocol. The effects of exact HF exchange on molecular dipole and charge transfer will also be discussed.

New protocol to assign partial atomic charges of water in condensed phase

ACS Fall 2020 Virtual Meeting

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