Structures and electronic properties of Cu20, Ag20, and Au20 clusters with density functional method

We have investigated the lowest-energy structures and electronic properties of the 20-atoms coinage metal clusters (Cu20, Ag20, and Au20) using density functional theory (DFT) within generalized gradient approximation. The most stable configurations obtained for Ag20 and Au20 clusters are tetrahedral structures Td symmetry), while compact structure with Cs symmetry is preferred for Cu20. Large HOMO–LUMO gap is found for Au20 and Ag20 with tetrahedral structures, while it is much small in the Cu20 isomer with tetrahedral structures. The compact Cs structure of Cu20 has large gap comparable to that of Au20 with tetrahedral structure.