Tetsuya Taketsugu

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Understanding a chemical reaction ultimately requires the knowledge of how each atom in the reactants moves during product formation. Such knowledge is seldom complete and is often limited to an oversimplified reaction coordinate that neglects global motions across the molecular framework. To overcome this limit, we recorded transient impulsive Raman(More)
Finding all required transition state (TS) structures is an important but hard task in theoretical study of complex reaction mechanisms. In the present article, an efficient automated TS search method, artificial force induced reaction (AFIR), was extended to intramolecular reactions. The AFIR method has been developed for intermolecular associative(More)
The adsorption of ethylene molecule on neutral, anionic and cationic gold clusters consisting of up to 10 atoms has been investigated using density-functional theory. It is demonstrated that C 2 H 4 can be adsorbed on small gold clusters in two different configurations, corresponding to the π-and di-σ-bonded species. Adsorption in the π-bonded mode(More)
A new type of reaction pathway which involves a nontotally symmetric trifurcation was found and investigated for a typical SN 2-type reaction, NC(-)  + CH3 X → NC-CH3  + X(-) (X = F, Cl). A nontotally symmetric valley-ridge inflection (VRI) point was located along the C3 v reaction path. For X = F, the minimum energy path (MEP) starting from the transition(More)
It is demonstrated that electrochemical hydrogen evolution reaction (HER) proceeds very efficiently at Au electrode, an inert substrate for HER, modified with BNNS, an insulator. This combination has been reported to be an efficient electrocatalyst for oxygen reduction reaction. Higher efficiency is achieved by using the size controlled BNNS (<1 μm) for the(More)
The existence of a valley-ridge transition (VRT) point along the intrinsic reaction coordinate does not always indicate the existence of two minima in the product side, but VRT is a sign of bifurcating nature of dynamical trajectories running on the potential energy surface. It is demonstrated by molecular dynamics simulations.
A global reaction route map is generated for Au5 by the anharmonic downward distortion following method in which 5 minima and 14 transition states (TSs) are located. Through vibrational analyses in the 3N - 7 (N = 5) dimensional space orthogonal to the intrinsic reaction coordinate (IRC), along all the IRCs, four IRCs are found to have valley-ridge(More)
On-the-fly dynamics simulations were carried out using spin-flip time dependent density functional theory (SF-TDDFT) to examine the photoisomerization and photocyclization mechanisms of cis-stilbene following excitation to the ππ* state. A state tracking method was devised to follow the target state among nearly degenerate electronic states during the(More)
An ab initio molecular dynamics approach is combined with the semiclassical tunneling method of Makri and Miller, which is applied to estimations of tunneling splitting in the umbrella inversion of ammonia and the intramolecular hydrogen transfer in malonaldehyde. In the application to malonaldehyde, effects of multidimensionality are examined by assigning(More)