Electronic and magnetic structure of CO on nickel clusters

Abstract

Spin-polarized self-consistent-field local-spin-density scattered-wave calculations have been performed for a variety of small nickel clusters and for these clusters interacting with CO adsorbed on top, bridge or hollow sites. In all cases, as is observed experimentally, adsorption causes a decrease in the magnetic moments of Ni atoms near the adsorption site. The mechanism for this change in the magnetism has been elucidated. Although the fine details vary somewhat from site to site, the primary cause is the same in all cases. Part of the Ni d density of states, in both spins, is destabilized through antibonding interactions with CO σ electrons and subsequently emptied. This triggers a spin-dependent rearrangement of the d electrons which leads to the decreased magnetism. These magnetic aspects have been integrated into an overall Ni-CO bonding scheme which is qualitatively consistent with available experimental data and with the results of more elaborate calculations when the latter are available.