Quantifying the relevance of long-range forces for crystal nucleation in water

TL;DR

This study investigates the roles of short- and long-range interactions in water crystal nucleation using advanced simulation techniques, revealing that short-range forces primarily drive nucleation while long-range forces stabilize the crystal state.

Contribution

It introduces a combined approach using local molecular field theory, metadynamics, and deep learning to disentangle the effects of different interactions in water nucleation.

Findings

Short-range interactions largely govern the two-step nucleation process.

Long-range interactions contribute to the stability of the primary crystal.

Analysis of reaction coordinates highlights the importance of long-range forces for metastability.

Abstract

Understanding nucleation from aqueous solutions is of fundamental importance in a multitude of fields, ranging from materials science to biophysics. The complex solvent-mediated interactions in aqueous solutions hamper the development of a simple physical picture elucidating the roles of different interactions in nucleation processes. In this work we make use of three complementary techniques to disentangle the role played by short and long-range interactions in solvent mediated nucleation. Specifically, the first approach we utilize is the local molecular field (LMF) theory to renormalize long-range Coulomb electrostatics. Secondly, we use well-tempered metadynamics to speed up rare events governed by short-range interactions. Thirdly, deep learning-based State Predictive Information Bottleneck approach is employed in analyzing the reaction coordinate of the nucleation processes obtained from LMF treatment coupled with well-tempered metadynamics. We find that the two-step nucleation mechanism can largely be captured by the short-range interactions, while the long-range interactions further contribute to the stability of the primary crystal state at ambient conditions. Furthermore, by analyzing the reaction coordinate obtained from combined LMF-metadynamics treatment, we discern the fluctuations on different time scales, highlighting the need for long-range interactions when accounting for metastability.