The polar (112) and (-1-1-2) surfaces of CuFeS2 were found to be remarkably stable. These surfaces were predicted to have sizable presence in equilibrium crystallite structures, regardless of the growth conditions. Their chemical properties therefore will significantly influence Cu dissolution rates.
The ultimate aim of the project is to elucidate chemical mechanisms associated with the dissolution of Cu from chalcopyrite (CuFeS2) in the context of hydrometallurgical leaching. This first involved hybrid exchange DFT study of bulk and surface systems of CuFeS2 to understand fundamental properties. For the bulk, the ground state geometric, magnetic and electronic properties have been documented and compared to available experimental results to validate the DFT methodology. The surface morphology of CuFeS2 has been investigated to identify key stable surfaces which are likely to be exposed upon cleavage. In the final part of the project, a QM/MM embedded cluster methodology has been developed and systematically tested with the ultimate aim of applying it to relevant solid-liquid systems to study Cu dissolution. In the methodology a combination of appropriately parametrized external embedding charges and atomic centered point charges were used to reproduce the periodic electrostatic potential of the original periodic system.