Comparative assessment of the ELBA coarse-grained model for water

Abstract

The ELBA force field for water consists of a single spherical site embedded with a point dipole. This coarse-grained model is assessed here through the calculation of fundamental properties of bulk liquid water and the water–vapour interface. Accuracy and efficiency are evaluated and compared against simulations of standard three- and four-site atomistic models. For bulk liquid systems, ELBA reproduces accurately most of the investigated properties. However, the radial distribution function deviates from atomistic and experimental data, indicating a loss of local structure. The water–vapour interface, simulated over a range of temperatures from 300 to 600 K, is captured realistically in terms of its density distribution, and the accuracy in reproducing the experimental surface tension is as high as that of the best atomistic model. The critical temperature of ELBA is also found to be in excellent agreement with experiment. However, the interfacial electric field and surface potential are missing. The computational speed-up of ELBA compared to traditional atomistic models is estimated to be between one and two orders of magnitude.