Docking of an asphaltene molecular model on a Fe2O3 surface, an Ab initio simulated annealing

The docking of an asphaltene molecular model over the (1000) hematite surface is analyzed through the use of ab initio molecular dynamics simulation techniques where the Density Functional Theory (DFT) forces were obtained using the Harris functional approach. The (1000) hematite surface is modeled by a supercell slab lattice of 225 atoms with a = b lengths of 25.17 Angstrom; on the c-direction an empty gap space and Fe-O-Fe-Fe-O atomic sequence was built. This structure was thermally stabilized at 400K. The asphaltene-hematite surface interaction was simulated with an annealing process at 400K during 555fs, and then a geometry optimization process was carried out on the final annealed configuration in order to stabilize the asphaltene-surface system. We find an attractive interaction between the asphaltene and the Fe2O3 which is located mainly at the asphaltene aromatic region. Finally, we have obtained cohesion energy of -417kcal/mol, indicative of quimisorption energy on the basis of a Harris functional treatment.