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

Abstract

The electronic structure and geometry of clusters of the type K_n, ${\text{K}}_n^{+}$, K_nCu_m and ${\text{K}}_n{\text{Cu}}_m^{+}$ (n, m ⩽ 4) were theoretically investigated and compared with similar clusters containing lithium atoms, using density functional methods. The K_nCu_m 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 K_n and K_nCu_m clusters follow the same trend, but the bimetallic clusters are more stable than K_n clusters. However, the global stability of K_n and K_nCu_m clusters is minor in comparison with corresponding lithium clusters.