Theoretical studies of the interactions of ethylene and formaldehydewith gold clusters

摘要

We studied the adsorption of C_2H_4and CH_2O on the gold clusters Au_n,(n=1-5)in variousadsorption modes using density functional theory PW91 functional. We found that the bindingenergies of π-C_2H_4and πand O-σ modes of CH_2O increase first and then decrease with the clustersize. Natural bonding orbital (NBO) analyses reveal that the donor-acceptor interaction plays animportant role in these adsorption complexes and there is a nice linear relationship between thecalculated binding energy and the stabilization energy estimated with second-order perturbationtheory in the framework of NBO analysis. It is demonstrated that the bonding interaction betweenadsorbates and clusters follows the di-σ> O-σ mode. However, due to adsorption inducedstructural deformation of adsorbates and clusters, the binding energies of different adsorption modesare comparable. It is shown that C_2H_4interacts more strongly with the clusters than CH_2O does andthat the previously assigned adsorption mode of C_2H_4on Au/MgO may not be thear modes, but C-σ configuration.