Phase transitions and nucleation processes

Not too far from coexistence, first order phase transitions such as the freezing or condensation proceed by a mechanism of nucleation of growth. A qualitative picture of this process is provided by classical nucleation theory, which asserts that the transformation proceeds via the formation of a localized nucleus of the stable phase growing in the metastable phase. Due to the free energetic cost creating an interface between the two phases, the free energy of this process displays a barrier that prevents the rapid transformation to the stable phase. While classical nucleation theory provides a provides a rough picture on the nucleation process, it usually fails on a quantitative level. In our group, we use rare event simulation methods to study the thermodynamics, kinetics and microscopic mechanism of nucleation processes. Recent work has focused on cavitation of water under negative pressures and the freezing of supercooled water.

^{S. Jungblut and C. Dellago, “Crystallization on pre-structured seeds“, Phys. Rev. E, 87, 012305 (2013).
G. Menzl, M.A. Gonzalez, P. Geiger, F. Caupin, J.L.F. Abascal, C. Valeriani, and C. Dellago, “Molecular mechanism of cavitation in water under tension”, Proc. Natl. Acad. Sci. USA 113, 13582-13587 (2016).
B. Cheng, C. Dellago, and M. Ceriotti, “Theoretical prediction of the homogeneous ice nucleation rate: disentangling thermodynamics and kinetics”, Phys. Chem. Chem. Phys. 20, 28732-28740 (2018).}