Density functional study of Au$_n$ (n=2-20) clusters: lowest-energy structures and electronic properties

摘要

We have investigated the lowest-energy structures and electronic propertiesof the Au$_n$(n=2-20) clusters based on density functional theory (DFT) withlocal density approximation. The small Au$_n$ clusters adopt planar structuresup to n=6. Tabular cage structures are preferred in the range of n=10-14 and astructural transition from tabular cage-like structure to compactnear-spherical structure is found around n=15. The most stable configurationsobtained for Au$_{13}$ and Au$_{19}$ clusters are amorphous instead oficosahedral or fcc-like, while the electronic density of states sensitivelydepend on the cluster geometry. Dramatic odd-even alternative behaviors areobtained in the relative stability, HOMO-LUMO gaps and ionization potentials ofgold clusters. The size evolution of electronic properties is discussed and thetheoretical ionization potentials of Au$_n$ clusters compare well withexperiments.