DFT study on stability and structure of bimetallic AumPdn (N = 38, 55, 79, N = m + n, m/n ≈ 2:1 and 5:1) clusters

The geometry and stability of the AumPdn bimetallic cluster have been studied using density functional theory with the GGA-PW91 exchange–correlation functional. A series of AumPdn (N = 38, 55, 79, N = m + n, m/n ≈ 2:1 and 5:1) bimetallic clusters with truncated octahedral shape was used to model such bimetallic nanosystems. The excess energy of two ratios configurations demonstrates that the m/n ≈ 2:1 ratio of AumPdn clusters is more stable than the m/n ≈ 5:1 ratio. The excess energy order of AumPdn clusters with the m/n ≈ 2:1 ratio is Au24Pd14 > Au52Pd27 > Au36Pd19, which shows a complicated size dependency. The Au24Pd14 cluster for N = 38 is the most stable bimetallic geometry. Hirshfeld charges and electron density difference show that the charge transfers from the Pd atoms to the Au atoms associated with the ionic feature of Au–Pd bonds. The PDOS, IP and EA show the sensitivity to Au:Pd ratio and cluster size N of AumPdn clusters. Such nanocrystallites are expected to exhibit peculiar catalytic properties and should be prone to retaining their initial shape under catalytic conditions due to the thermodynamically stability.