Structural Evolution of Cadmium Selenide Clusters: An Unbiased Global Optimization Study of (CdSe) N for 5 ≤ N ≤ 80

Thestructures of large cadmium selenide clusters are poorly understooddue to the presence of challenging long-range Coulombic interactionsand a vast number of possible structures. In this study, we presentan unbiased fuzzy global optimization method that incorporates atom-pairhopping, ultrafast shape recognition, and adaptive temperatures withina directed Monte Carlo framework to enhance the search efficiencyof binary clusters. Using this method and first-principles calculations,we successfully obtain the lowest-energy structures of (CdSe)( N ) clusters with 5 & LE; N & LE; 80. The putative global minima reported in the literaturehave been obtained. The binding energy per atom tends to decreasewith cluster size. Our results show that the stable structures evolvefrom rings to stacked rings, cages, nanotubes, cage-wurtzite, cage-core,and finally wurtzite structures, enabling us to reveal a systematicstructural evolution for the growth of cadmium selenide clusters withoutligands.