Water is one of the simplest molecules in existence, but also one of the most important in biological and engineered systems. However, understanding the structure and dynamics of liquid water remains a major scientific challenge.
Molecular dynamics simulations of liquid water can be used to calculate the radial distribution functions (RDFs), the relative angular distributions, and the excess enthalpies,entropies, and free energies. The TIP5P-Ewald model demonstrates an increased preference for water molecules to act both as tetrahedral hydrogen bond donors and acceptors, whereas the SWM4-NDP model demonstrates an increased preference for water molecules to act as planar hydrogen bond acceptors.
These differences are not uncovered by analysis of the RDFs or the commonly employed tetrahedral order parameter. However, they are expected to be very important when considering water molecules around solutes and are thus a key consideration in modelling solvent entropy. We are validating existing water models and developing new water models using experimental data and quantum mechanical calculations.