Atomistic simulation of mineral surfaces: Studies of surface stability and growth

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Abstract
Atomistic simulation represents a valuable methodology for interpreting and predicting surface structures. The emphasis of our work is to develop and apply this approach to understanding the role of surface defects and additives in modifying the structure and stability of mineral surfaces. The basis of our approach is energy minimisation which allows us to evaluate the most stable surface configurations. The utility and limitations of this approach will be illustrated via a number of examples. These include describing the factors governing the stability of mineral surfaces and applying these considerations to understanding the surfaces of olivine and spinel. In addition, we are beginning to address the water-solid interface. We find a wide variation in the reactivity of the different surfaces of rock-salt oxides from (100) which show only physisorption, through stepped surfaces which show dissociative adsorption to (111) which forms the hydroxide. One way of determining the interaction between surfaces and additives is the modification of crystal growth thus we are also concerned with attempting to model the growth process. However, the low index surfaces often grow via screw dislocations. Therefore preliminary work on modelling the interaction of screw dislocations with surfaces of MgO will be described.