Electronic properties of small Kn (n ⩽ 8) and bimetallic KnCum (n, m ⩽ 4) clusters

The electronic structure and geometry of clusters of the type Kn, Kn+, KnCum and KnCum+ (n, m ⩽ 4) were theoretically investigated and compared with similar clusters containing lithium atoms, using density functional methods. The KnCum bimetallic system is important to understand the promotion effects of the alkali atoms on the copper surface. The inclusion of potassium atoms on a bare copper cluster tends to break the Cu-Cu bond when n ⩾ m favors the formation of polar K-Cu bonds. The geometrical shape of Kn and KnCum clusters follow the same trend, but the bimetallic clusters are more stable than Kn clusters. However, the global stability of Kn and KnCum clusters is minor in comparison with corresponding lithium clusters.