Geometries and stabilities of Ag n v (v = ±1, 0; n = 21–29) clusters

摘要

We performed a systematical study on the lowest-energy structures of the medium-sized silver clusters Ag n (n = 21–29) by using a genetic algorithm coupled with a tight-binding method, and the DFT calculations with Perdew–Wang generalized-gradient approximation. The corresponding cluster ions were also searched based on the neutral cluster structures. It is found that the Ag21–23 prefer icosahedron or double-icosahedron as core structures. Ag n (n = 24–27) favor a bulk-like fcc stacking motif. Ag28 and Ag29 tend to high symmetrical structures. The relative stabilities, the ionization potentials and electronic affinities of silver clusters analyzed in the paper are consistent with the experimental data. It is interesting to find that the experimental spectra fit reasonable well the optical absorption spectra obtained with the structures calculated by us.