Four-to-one coarse-grained polarisable water model for dissipative particle dynamics

An accurate description of long-ranged electrostatics in molecular simulations necessitates the solvent models that respond in accordance with the local electric fields. Given this fact, many polarisable versions of water models exist for molecular dynamics simulations. However, there is only one model of water which is polarisable available for dissipative particle dynamics (DPD) simulations, and it is based on three-to-one coarse-graining scheme. The recent coarse-grained models of lipids meant for biomembrane studies using DPD are MARTINI-like models and have level of coarse-graining four-to-one. So a polarisable model of water needed to study the biological processes in conjunction with these lipid models should also be of the same degree of coarse-graining. Therefore, we present a DPD model of polarisable water with degree of coarse-graining four-to-one. By reflecting the positions of two Drude oscillators, the model responds to local electric fields, setting up induced polarisation locally. The model parameters are to reproduce the relative dielectric permittivity and compressibility of water at room temperature. The validity and applicability of the water model have been ascertained through in-silico evidences presented.