Application of ONIOM to cluster modeling of the metal surface

The applicability and reliability of the ONIOM framework in modeling metal surface were first examined in the present study. Both two- and three-layer ONIOM methodology are found economical and reliable. The first nearest coordinate metal atoms of those forming adsorption sites, which play a key role in determining the adsorption energies, are required to be described by an accurate high level method, while a low level method can be applied to the second nearest neighbor or farther atoms.