Molecular Simulations of Crystallization and Self-Assembly
Seminar by Peter G. Kusalik, University of Calgary, Alberta, Canada
Crystallization and self-assembly processes are ubiquitous in nature and have numerous important roles in technological applications. For example, predicting the nucleation of water droplets in clouds is crucial to weather and climate modelling. Yet, these ordering processes have proven difficult to study with experiments, in part due to their stochastic nature. Molecular simulations have recently been demonstrated to be able to provide many insights into the underlying molecular mechanisms. In this presentation I will begin with a brief review of the key issues around simulations of crystallization, considering briefly the attributes and limitation of various models and methods, as well as parameters used to measure order in systems. I will describe some approaches we have developed and utilized for the simulation of the formation and growth of crystals, both in the homogeneous and heterogeneous contexts. Specific results for gas (clathrate) hydrates and for ice will be used illustratively. These results will demonstrate that the process of crystallization is characterized by collective phenomena involving many molecules. The nature of the structural fluctuations that characterize these ordering processes, including lifetimes and transitions of specific structures (e.g. cages), will be examined, and I will show how defects can play key roles in the observed behaviours. More generally, I will show how rugged funnel-shaped potential energy landscapes, a representation used widely to help describe protein folding, provide a lens for understanding the phenomenology of crystal nucleation in gas hydrates and ice. I will conclude with an exploration of self-assembly processes of metal organic framework (MOF) materials. The key features of the observed behaviour will be examined, and then compared and contrasted with that found for other systems.
KC, lecture hall, Kemi, Campus Johanneberg
15 March, 2018, 12:00
15 March, 2018, 13:00