Structure and structural evolution of () clusters using a genetic algorithm and density functional theory method

Using a genetic algorithm followed by local optimization with density functional theory, the lowest-energy structures of Ag n clusters in a size range of n = 3 – 22 were studied. The Ag n ( n = 9 – 16 ) clusters prefer compact structures of flat shape, while the Ag n ( n = 19 , 21 , 22 ) clusters adopt amorphous packing based on a 13-atom icosahedral core. For Ag 16 , two competitive candidates for the lowest-energy structures, namely a hollow-cage structure and close-packed structures of flat shape, were found. Two competing candidates were found for Ag 17 and Ag 18 : hollow-cage structures versus icosahedron-based compact structures. The lowest-energy structure of Ag 20 is a highly symmetric tetrahedron with T d symmetry. These results are significantly different from those predicted in earlier works using empirical methods. The ionization potentials and electron affinities for the lowest-energy structures of Ag n ( n = 3 – 22 ) clusters were computed and compared with experimental values.