Adhesion energy of Cu atoms on the MgO(001) surface

We have studied theoretically the interaction of an isolated Cu atom adsorb ed on the oxygen sites of the regular MgO (001) surface with the aim of pro viding an accurate estimate of the adhesion energy. We performed cluster mo del calculations using a variety of first principles quantum-chemical appro aches; local (spin) density approximation [L(S)DA], density functionals tha t include density gradient corrections (GC-DF), hybrid density functional ( B3LYP), and explicitly correlated wave functions. Various combinations of e xchange-correlation functionals and different methods to introduce electron correlation, including MP2 and CCSD(T), have been considered. The dependen ce of the results on cluster and basis set size has been carefully checked. We found that the hybrid DF method, B3LYP, and explicitly correlated wave functions, CCSD(T), give similar results with an adhesion energy of about 0 .40+/-0.05 eV; GC-DF methods suggest a higher binding energy of 0.6 eV. The refore, Cu atoms can be considered to bind to oxygen centers of the ideal M gO (001) surface in a relatively weak chemical fashion, in broad agreement with the low sticking coefficient measured experimentally. (C) 1999 America n Institute of Physics. [S0021-9606(99)70209-6].