Atomistic simulation of mineral surfaces

Atomistic simulation techniques are now able to model the structure of mine ral surfaces at the atomic level. In this paper we begin to address the que stion of whether surface reactivity can be studied reliably by modelling th e surface reactivity of calcite, fluorite and forsterite under aqueous cond itions. We first used energy minimisation techniques to investigate the int eraction between the minerals calcite and fluorite with water and methanoic acid. The relative adsorption energies suggest that methanoic acid prefere ntially adsorbs onto fluorite surfaces, while water adsorbs preferentially onto calcite as inferred from experiments on mineral separation. Molecular Dynamics simulations were also used to model the effect of temperature on t he adsorption of water on the calcite {10 (1) over bar 4} and fluorite {111 } surfaces. Furthermore we used these techniques to model point defect form ation at surfaces. We are also interested in modelling the competition betw een associative and dissociative adsorption on mineral surfaces. Simulation s of adsorption of water on the low-index forsterite surfaces have predicte d the adsorption energies and equilibrium morphology. The calculated equili brium morphology adequately reproduces the experimental morphology of forst erite suggesting that the relative stabilities of the surfaces, both unhydr ated and hydroxylated, are calculated correctly.