Molecular dynamics simulations are invaluable tools in the study of the mineral-water interface. Specialized sampling methods further promise to provide mechanistic insights into the kinetics of interfacial reactions that drive mineral dissolution and growth. At present, the capacity to simulate rare events in such complex systems is limited by the ability to accurately characterize multi-dimensional energy landscapes, and to identify important stable and metastable states and the transition pathways between them. Current approaches generally require either some degree of a priori knowledge of the energy landscape (i.e. important collective variables), or possession of an initial reactive pathway. These requirements place significant restrictions on the ability to probe complex dynamic processes with atomistic simulations. Namely, the computational effort required to characterize the landscape can easily exceed the limits of practicality, and reducing the complexity of the landscape down to manageable number of collective variables is not always intuitive or feasible. Our group is developing a path sampling method, based on the forward flux sampling procedure, that does not require foreknowledge of the energy landscape or an initial reactive path, and eliminates the need to use collective variables to drive transitions between stable states. Herein we present the results of our initial application of this method to the kinetics of water exchange on Li+, Ca2+ and Mg2+, and demonstrate the method’s potential utility in investigations of ligand exchange reactions at the mineral-water interface.

Application of a novel forward flux sampling procedure to the kinetics of water exchange on Li+, Ca2+ and Mg2+

256th National Meeting (2018)

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