OH frequency calculations for the hydroxylated MgO(001) surface

We have performed periodic Hartree-Fock calculations for OH groups adsorbed on the MgO(001) surface considering different surface coverages. Six types of OH groups are discussed: OH-, OH, H+, H and hydrogen-bonded OH and H. It is found that when both OH and H are present on the surface, the two groups are best described as OH-. We suggest that the highest-frequency fundamental band (similar to3750 cm(-1) in the experimental OH spectrum) is assigned to OH- groups adsorbed on top of Mg2+, while H+ adsorbed on top of O2- give rise to the broader band at similar to3550 cm(-1).