Correlated Wave Function Calculations of the Chemisorption of Water on a Clean Titanium (0001) Surface.

The Hartree-Fock-Roothaan Self-Consistent-Field (SCF) Method supplemented by configuration interaction (CI) was used to study the interaction and dissociation of a water molecule on a Titanium surface. The calculations were made tractable by using a Ti core potential and by a unitary localization transformation to define a local surface region of localized lattice plus adsorbate orbitals for the CI calculations. Three Ti clusters were considered Ti(,3), Ti(,7) and Ti(,28). The dissociated H(,2)O (OH + H) was found to be bound on the three clusters with binding energy ranging from 25 K cal/mol to 36 K cal/mol. The 3 d electrons were shown to play a limited role in bonding and to create an activation barrier for molecular H(,2)O as it approaches the surface. The completely dissociated H(,2)O (O + 2H) was found to be unbound indicating that atomic oxygen derived from H(,2)O does not exist on the surface.