ATOMISTIC SIMULATION OF MINERAL SURFACES - STUDIES OF SURFACE STABILITY AND GROWTH

Atomistic simulation represents a valuable methodology for interpretin g and predicting surface structures. The emphasis of our work is to de velop and apply this approach to understanding the role of surface def ects and additives in modifying the structure and stability of mineral surfaces. The basis of our approach is energy minimisation which allo ws us to evaluate the most stable surface configurations. The utility and limitations of this approach will be illustrated via a number of e xamples. 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 rea ctivity of the different surfaces of rock-salt oxides from {100} which show only physisorption, through stepped surfaces which show dissocia tive adsorption to {111} which forms the hydroxide. One way of determi ning the interaction between surfaces and additives is the modificatio n of crystal growth thus we are also concerned with attempting to mode l the growth process. However, the low index surfaces often grow via s crew dislocations. Therefore preliminary work on modelling the interac tion of screw dislocations with surfaces of MgO will be described.