Hollow polyhedral structures and properties of AgS (n = 2-11) clusters: A theoretical study.

CONTEXT

The structures of AgS (n = 2-11) clusters are obtained by the combination of genetic algorithm (GA) and density functional theory (DFT). All the global minimum structures prefer hollow polyhedral structures, in which S-Ag-S element, triangular AgS and tetragonal AgS units present to stabilize the structures. The S atoms in the structures appear in μ-S or μ-S form. Adiabatic and vertical electron affinities of the clusters have been obtained, which reveals that they increases as cluster size. Stability analysis shows that AgS and AgS have special stability. The HOMO, LUMO orbitals of the clusters are obtained and the orbital components of them are calculated. The HOMO orbitals are mainly from the p orbitals of S atoms, whereas the s, p and d orbitals of Ag atoms contribute much bigger than the p orbitals of S atoms for LUMO orbitals. The orbital delocalization indexes (ODI) of the HOMOs and LUMOs are calculated, and the small ODIs of the HOMOs and LUMOs for n = 4-10 reveal that these orbitals are highly delocalized. By studying the projected density of states and molecular orbitals of AgS and AgS clusters, it is found that their molecular orbitals have superatomic properties. Superatomic properties play an important role in stabilizing clusters.

METHODS

This work used combined genetic algorithm and density functional theory (GA-DFT), and PBE0/Lanl2tz(Ag)/6-311G(d,p)(S) method to optimize the structures. Gaussian 16 program, Gauss view 6.0.16 program and Multiwfn 3.8 code are the softwares used.