Validation study of the ability of density functionals to predict the planar-to-three-dimensional structural transition in anionic gold clusters.

As gold clusters increase in size, the preferred structure changes from planar to three-dimensional and, for anionic clusters, Au_n^-, the two-dimensional(2D)→three-dimensional (3D) transition is found experimentally to occur between n=11 and n=12. Most density functionals predict that planar structures are preferred up to higher n than is observed experimentally, an exception being the local spin density approximation. Here we test four relatively new functionals for this feature, in particular, M05, M06-L, M06, and SOGGA. We find that M06-L, M06, and SOGGA all predict the 2D→3D transition at the correct value of n. Since the M06-L and M06 functionals have previously been shown to be reasonably accurate for transition metal bond energies, main group atomization energies, barrier heights, and noncovalent interaction energies, and, since they are here shown to perform well for the s-d excitation energy and ionization potential of Au atoms and for the size of Au_n^- clusters at which the 2D→3D transition occurs, they are recommended for simulating processes catalyzed by gold clusters. [ABSTRACT FROM AUTHOR]