Application of the method of increments to the adsorption of CO on the CeO2(110) surface.

We have combined an embedded-cluster model with an extension of the method of increments to treat the adsorption of molecules on a surface. In this way we are able to investigate the physisorption of CO on CeO(2)(110) at the MP2, MP4(SDTQ), and CCSD(T) levels with only moderate computational costs. We find that, at the CCSD(T) level, 25% of the adsorption energy originates from electron correlation. The interactions of the CO molecule with its five nearest cerium and oxygen neighbors in the surface layer make the largest contributions to the electron correlation. Approximately 97% of the adsorption-induced electron correlation energy part of the adsorption energy is recovered by the method of increments (in our chosen expansion), at the MP2 level.