PNNL

Abstract

The structure of gas-phase gold clusters of size ~ 20 is studied by density-functional global optimization in the full configuration space. The global minimum of Au20 is confirmed to be a tetrahedron (Td) independently of the choice of exchange-correlation functional, whereas the structure of low-lying excited states depends on the theoretical approach. The peculiar stability of Td is rationalized in terms of the synergic effects of s-d hybridization and electronic shell closing. Calculations on Au16 and Au18 show that Td Au20 possibly represents an “unicum” in the sequence of gold clusters.