Role of dispersive interactions in the CO adsorption on MgO(001): periodic B3LYP calculations augmented with an empirical dispersion term.

Empirically dispersion corrected B3LYP method (i.e. B3LYP-D) is demonstrated to give excellent results for structure, adsorption energy and vibrational frequency shift for the CO molecule adsorbed on the MgO(001) surface, a system considered a challenge for current density functional methods. A periodic approach was adopted to model the interaction using a three-layer slab model. For the B3LYP-D* method an interaction energy of -13.1 kJ mol(-1) is computed at low-coverage in very good agreement with experimental evidence (-12.6 kJ mol(-1)) as well as a positive CO vibrational shift of 10 cm(-1) to be compared with the experimental value of 14 cm(-1).