Stress testing the ELBA water model

Abstract

The ELBA coarse-grained model describes a water molecule as a single-site Lennard-Jones particle embedded with a point dipole. ELBA was previously reported to capture several properties of real water with relatively high accuracy, while being up to two orders of magnitude more computationally efficient than atomistic models. Here, we ‘stress test’ the ELBA model by investigating the temperature and pressure dependences of two most important water properties, the liquid density and the self-diffusion coefficient. In particular, molecular dynamics simulations are performed spanning temperatures from 268 K up to 378 K and pressures from 1 atm up to 4000 atm. Comparisons are made with literature data from experiments and from simulations of traditional three-site atomistic models. Remarkably, the ELBA results show an overall similar (and sometimes higher) accuracy with respect to the atomistic data. We also calculate a number of additional thermodynamic properties at ambient conditions, namely isothermal compressibility, shear viscosity, isobaric heat capacity, thermal expansion coefficient and melting point. The accuracy of ELBA is relatively good compared to atomistic and other coarse-grained models.