DFT investigation of Au9M2+ nanoclusters (M = Sc-Ni): The magnetic superatomic behavior of Au9Cr2+

Binding energy per atom (BE) of Au 9 M 2+ clusters and AuM dimers normalized with those of Au 10 2 + and Au 2 , respectively. Au 9 Sc 2+ and Au 9 Ti 2+ prefer the type-I (endohedral cage-like) structure, while Au 9 M 2+ (M = V, Cr, Mn, Fe, Co, and Ni) favor the type-II (tetrahedral) one. • The structural evolution of Au 9 M 2+ is ruled by the bond strength of AuM dimers. • The cage-like structure for M = Sc and Ti and the tetrahedral structure for heavier ones. • The exceptionally stable Au 9 Cr 2+ is identified as a potential magnetic superatom. Au 10 2 + has been found very stable showing a superatomic behavior with a highly symmetrical geometry and can be considered as the smallest copy of the golden pyramid Au 20 . In this work, we further explore superatomic clusters as analogues of more complex molecules by doping Au 10 2 + cluster with 3 d transition metal atom. It is found that, in similarity to their sister Au 19 M, the structural evolution of Au 9 M 2+ is ruled by the bond strength of AuM dimers and can be generalized into two motifs: the endohedrally doped cage-like structure for lighter dopants (M = Sc and Ti) and the slightly distorted tetrahedral structure for heavier ones. The average binding energies and dissociation energies are calculated to identify the relatively stable patterns. The molecular orbital (MO) diagram as well as the spin distribution are computed to understand the electronic structure and magnetic behavior of studied clusters. The spin magnetic moments of Au 9 M 2+ clusters systematically vary from 0 to 5 μ B , depending on the localization of unpaired 3 d electrons. With a large spin magnetic moment of 5 μ B , the exceptionally stable Au 9 Cr 2+ is identified as a potential magnetic superatom and would be beneficial for further theoretical and experimental studies.