Title:	Interplay between structure and dynamics of water
DNr:	NAISS 2026/3-270
Project Type:	NAISS Medium
Principal Investigator:	Vitaly Kocherbitov <vitaly.kocherbitov@mau.se>
Affiliation:	Malmö universitet
Duration:	2026-04-28 – 2027-05-01
Classification:	10402 10304 10407
Keywords:

Abstract

Water is arguably the most important substance on Earth. Due to its ubiquity, it strongly influences the properties of all molecules it interacts with and mediates intermolecular interactions. Therefore, understanding the structural and dynamical properties of water is essential for describing systems ranging from simple liquids to complex biomolecules such as carbohydrates and proteins. Water exhibits unique structural, thermodynamic, and dynamical anomalies, particularly in the supercooled regime, where transformations between high-density and low-density liquid environments occur alongside kinetic arrest. Experimental studies in this regime are severely limited by rapid crystallization, making molecular simulations the primary tool for investigating deeply supercooled liquid water. In this project, we employ molecular dynamics (MD) simulations with controlled cooling and heating scans to investigate the coupling between equilibrium and non-equilibrium behavior of water. Our preliminary results indicate that the glass transition temperature occurs in a similar range as the structural transformation often associated with the high-density to low-density liquid transition. While the structural transition appears largely independent of scan rate, the dynamical transition (glass transition) exhibits strong scan-rate dependence. We hypothesize that systematic variation of scan rates enables separation of structural and dynamical contributions to apparent thermodynamic properties, such as heat capacity. Achieving this requires simulations spanning a wide range of scan rates, which necessitates extensive computational resources. Our initial results suggest that scan rates from 10 to 3000 K µs⁻¹ are sufficient to resolve these contributions. We will perform large-scale MD simulations across multiple pressures to disentangle the glass transition from structural transformations and construct a consistent pressure–temperature phase diagram of supercooled water, a topic that remains under active debate. Furthermore, we will extend this approach to investigate the effects of confinement, system size, and solutes on the structural and dynamical properties of supercooled water.