Theoretical and computational approaches to study crystal nucleation from solution

Nucleation is the initial step towards the formation of crystalline materials from solutions. Various factors, such as environmental conditions, additives, and external forces, can influence its outcomes and rates. Indeed, controlling this rate-determining step towards phase separation can affect the material structure and properties, and it is crucial in a range of scientific fields. In this regard, atomistic simulation methods can be exploited to gain insight into nucleation mechanisms - an aspect difficult to ascertain in experiments - and estimate nucleation rates. However, the microscopic nature of simulations affects the phase behaviour of nucleating solutions when compared to macroscopic systems. Additionally, a challenge in modelling nucleation from solution is associated with the inadequacy of standard molecular simulations to access the timescales necessary to observe crystal nucleation due to the inherent rareness of these events. In recent decades, simulation methods have emerged to circumvent length- and timescale limitations. However, which simulation method is most suitable for studying crystal nucleation from solution is not always obvious. This review summarises the recent advances in this field, providing an overview of the typical nucleation mechanisms and the suitability of different simulation methods to study them. By doing so, we aim to provide a deeper understanding of the complexities associated with modelling crystal nucleation from solution and identify areas for further research. Our review targets researchers across various scientific fields, including materials science, chemistry, physics and engineering, and will hopefully contribute to developing new strategies for understanding and controlling nucleation.