Coupled-Cluster study of 'no-pair' bonding in the tetrahedral Cu4 cluster
Résumé
Ab initio Coupled-Cluster calculations with single and double excitations and perturbative correction to the triple, CCSD(T), have been carried out for the high-spin electronic state, View the MathML source, of the copper cluster Cu4 in its tetrahedral arrangement. Like alkali metals clusters, tetrahedral Cu4 presents a bound quintet state, i.e., a situation where all the valence electrons are unpaired. This rather exotic wavefunction, also known as no-pair bonding state, is examined in detail. The influence of the basis set is also analyzed, as well as the importance of the core correlation and the effect of the basis-set superposition errors.