How Many Isomers Do Metallic Clusters Have? Case of Magnesium Clusters of up to 55 Atoms.

About 9000 structures of magnesium clusters Mg ( = 2-13) generated via different methods were optimized at the DFT levels in order to estimate the number of all possible stable structures that can exist for the given cluster size (∼820,000 PES points were explored in total). It was found that the number of possible cluster isomers quickly grows with a number of atoms ; however, it is significantly lower than the number of possible nonisomorphic graph structures, which can be drawn for the given At the DFT potential energy surface, we found only 543 local minima corresponding to the isomers of Mg-Mg. The number of isomers obtained in the DFT optimizations grows with approximately as , whereas the values extrapolated to the infinite generation process grow as .