### Exploring the utility of coarse-grained water models for computational
studies of interfacial systems

Xibing He, __Wataru Shinoda__, Russell DeVane, and Michael L. Klein

Molecular Physics **108** 2007-2020 (2010)

Molecular dynamics simulations have become a standard tool for the investigation
of biological and soft matter systems. Water models serve as the basis
of force fields used in molecular dynamics simulations of these systems.
This article reports on an examination of the utility of a set of coarse-grained
(CG) water models, with different resolutions, interaction potentials (Lennard?Jones,
Morse), and cut-off distances. The relationships between the parameters
under specific choices of the above options and the thermodynamic properties,
such as density, surface tension, and compressibility, were found to fit
simple mathematical equations. The limits of applicability of these CG
water models were explored by checking the melting temperature. If a CG
site is mapped to one or two real water molecules, a simple model with
appropriate combinations of cut-off distances, functional forms, and parameters
can be found to simultaneously match the experimental values of density,
surface tension, and compressibility under ambient conditions. If more
water molecules are included in a CG site, either the melting temperature
approaches or surpasses room temperature, or the surface tension and compressibility
cannot both be matched simultaneously. In striving for computational efficiency,
it is still possible to find a simple CG water model with three water molecules
contained in a CG bead that generates a liquid state of water with realistic
values of density, surface tension and compressibility at ambient condition,
but coarser models are not recommended.