Application
of Automated Reaction Path Search Methods
to a Systematic Search of Single-Bond Activation Pathways Catalyzed
by Small Metal Clusters: A Case Study on H–H Activation by
Gold
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Abstract
A new
theoretical approach to find metal-cluster-catalyzed single
bond activation pathways is introduced. The proposed approach combines
two automated reaction path search techniques: the anharmonic downward
distortion following (ADDF) and the artificial force induced reaction
(AFIR) methods, developed in our previous works [Maeda, S.; Ohno,
K.; Morokuma, K. <i>Phys. Chem. Chem. Phys.</i> <b>2013</b>, <i>15</i>, 3683–3701]. A simple model reaction
of the H–H bond activation catalyzed by Au<sub><i>n</i></sub> (<i>n</i> = 7, 8) clusters is considered as an example.
We have automatically found 33 and 20 transition-state (TS) structures
for H<sub>2</sub> dissociation on Au<sub>7</sub> and Au<sub>8</sub> clusters, respectively, and successfully identified the best dissociation
pathways with the lowest barrier. Systematic analysis of the structure-dependent
reactivity of small gold clusters is performed. It is demonstrated
that the most stable structures of the gold clusters are not always
highly reactive and several isomeric structures must be taken into
account for adequate description of the reaction rates at finite temperatures.
The proposed approach can serve as a promising tool for investigation
of the chemical reactions catalyzed by small metal clusters