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].