Development of a ReaxFF Reactive Force Field for TitaniumDioxide/Water Systems.

A newReaxFF reactive force field has been developed to describereactions in the Ti–O–H system. The ReaxFF force fieldparameters have been fitted to a quantum mechanical (QM) trainingset containing structures and energies related to bond dissociationenergies, angle and dihedral distortions, and reactions between waterand titanium dioxide, as well as experimental crystal structures,heats of formation, and bulk modulus data. Model configurations forthe training set were based on DFT calculations on molecular clustersand periodic systems (both bulk crystals and surfaces). ReaxFF reproducesaccurately the QM training set for structures and energetics of smallclusters. ReaxFF also describes the relative energetics for rutile,brookite, and anatase. The results of ReaxFF match reasonably wellwith those of QM for water binding energies, surface energies, andH2O dissociation energy barriers. To validate this ReaxFFdescription, we have compared its performance against DFT/MD simulationsfor 1 and 3 monolayers of water interacting with a rutile (110) surface.We found agreement within a 10% error between the DFT/MD and ReaxFFwater dissociation levels for both coverages. [ABSTRACT FROM AUTHOR]