Structure and polymerization of liquid sulfur across the -transition

The anomalous lambda-transition of liquid sulfur, which is supposed to be related to the transformation of eight-membered sulfur rings into long polymeric chains, has attracted considerable attention. However, a detailed description of the underlying dynamical polymerization process is still missing. Here, we study the structures and the mechanism of the polymerization processes of liquid sulfur across the lambda-transition as well as its reverse process of formation of the rings. We do so by performing ab initio-quality molecular dynamics simulations thanks to a combination of machine learning potentials and state-of-the-art enhanced sampling techniques. With our approach, we obtain structural results that are in good agreement with the experiments and we report precious dynamical insights into the mechanisms involved in the process. We study the lambda liquid-liquid transition between molecular and polymeric phases of sulfur with molecular dynamics simulations boosted by state-of-the-art enhanced sampling techniques and ab initio-quality machine-learning potentials.