A Benchmark Study of H-2 Activation by Au-3 and Ag-3 Clusters
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We present a high-level computational study of the activation and disassociation of H2 on triatomic gold and silver clusters as well as benchmarks of various density functional theory (DFT) approximations. The reaction was modeled using complete basis set (CBS) extrapolated CCSD(T) energies at MP2/def2-QZVPP geometries. Our calculations considered several isomers of dissociated H2 on the metal trimer as well as transition states between them. High-level results were then used to benchmark 30 different semilocal, hybrid, double hybrid, and Rung 3.5 DFT functionals as well as Hartree-Fock and MP2 theory. The effect of optimizing the geometries using DFT was also studied with a smaller set of functionals. The results indicate that double-hybrid functionals, especially mPW2PLYP, accurately model this class of reactions, albeit at computational cost higher than standard DFT. The range-separated (screened) hybrids HSE06 and HISSb are also successful and provide a reasonable balance of computational cost and accuracy. These methods are particularly promising for treatments of coinage metal clusters and surfaces. 2013 American Chemical Society.
