Connection between water's dynamical and structural properties: Insights from ab initio simulations

C Herrero and M Pauletti and G Tocci and M Iannuzzi and L Joly, PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 119, e2121641119 (2022).

DOI: 10.1073/pnas.2121641119

Among all fluids, water has always been of special concern for scientists from a wide variety of research fields because of its rich behavior. In particular, some questions remain unanswered today regarding the temperature dependence of bulk and interfacial transport properties of supercooled and liquid water, for example, regarding the fundamentals of the violation of the Stokes-Einstein relation in the supercooled regime, or the subtle relation between structure and dynamical properties. We have studied the temperature dependence of the bulk transport properties from ab initio molecular dynamics based on density functional theory, down to the supercooled regime. We determined, from a selection of functionals, that the SCAN (strongly constrained and appropriately normed) functional best describes the experimental viscosity and selfdiffusion coefficient, although we found disagreements at lower temperatures. For a limited set of temperatures, we also explored the role of nuclear quantum effects on water dynamics using ab initio molecular dynamics that was accelerated by a recently introduced machine learning approach. We then investigated the molecularmechanisms underlying the different functionals' performance and assessed the validity of the StokesEinstein relation. We also explored the connection between structural properties and transport coefficients, verifying the validity of the excess entropy scaling relations for all functionals. These results pave the way for the prediction of the transport coefficients from the radial distribution function, thus helping to develop better functionals. In this respect, these results indicate the importance of describing the long-range features of the radial distribution function.

Return to Publications page