IQTC Seminar: Jayant K. Singh
Insight into the ice formation at extreme confinement and under shear flow
Friday May 26th 2023, 12:00h
Aula de Química Física
Understanding thermodynamics and kinetics of ice formation are relevant to numerous engineering, atmospheric, environmental, and biological systems, viz., soil, biological cells, flood, aircraft, transportation, and cloud formation. Thus, water and ice have been studied extensively over the last 100 years, yet the understanding is far from complete. Ice is now known to have more than 18 stable phases. In recent years, with the help of simulations and experiments, ice phase XVIII has been established, while recently, two more polymorphs have been reported, XIX and XX. Though numerous high-pressure and temperature ice polymorphs are discovered in the laboratory, the first experimental discovery of natural ice-VII on Earth reveals the diamond host crystal’s ability (confinement) to constrain the temperature and high pressure required for the formation of rare high-pressure ice polymorphs.
In the first part of the talk, I will describe the phase diagram of water and ice and some unique features/properties that have been discovered in recent years. Further, drawing inspiration from the formation of high-pressure ice in diamond inclusions, I will present our recent work on quasi-two-dimensional water’s structures and phase behaviour using molecular simulations under gigapascal-high pressure. In the second part of the talk, I will discuss the behavior of supercooled water near a superhydrophobic surface within the framework of necessary properties for an anti-ice surface, particularly addressing the impact of surface heterogeneity on the nucleation behavior of supercooled water. In the end, I will present a general formalism for calculating the nucleation rates of simply sheared systems. We have derived an extension to the conventional Classical Nucleation Theory, explicitly embodying the shear rate. The framework can be used for moderate supercooling, at which temperatures brute-force methods are practically infeasible. We show how the theory can be used to identify shear regimes of ice nucleation behavior for the mW water model, unifying disparate trends reported in the literature.
If you can’t come, join us on zoom: https://ub-edu.zoom.us/s/99663969041