Finding Reaction Pathways of Type A + B → X: Toward Systematic Prediction of Reaction Mechanisms

Abstract

In these five decades, many useful tools have been developed for exploring quantum chemical potential energy surfaces. The success in theoretical studies of chemical reaction mechanisms has been greatly supported by these tools. However, systematic prediction of reaction mechanisms starting only from given reactants and catalysts is still very difficult. Toward this goal, we describe the artificial force induced reaction (AFIR) method for automatically finding reaction paths of type A + B → X (+ Y). By imposing an artificial force to given reactants and catalysts, the method can find the reactive sites very efficiently. Further pressing by the artificial force provides approximate transition states and product structures, which can be easily reoptimized to the corresponding true ones. This procedure can be executed very efficiently just by minimizing a single function called the AFIR function. All important reaction paths can be found by repeating this cycle starting from many initial orientations. We also discuss perspectives of automated reaction path search methods toward the above goal.

Mechanisms for the Breakdown of Halomethanes through Reactions with Ground‐State Cyano Radicals

“…The stationary points of the CX3Y + CN potential energy surfaces were located using the AFIR algorithm, [5][6] implemented in a local development version of the Global Reaction Route Mapping (GRRM) program. The AFIR method systematically explores the potential energy surface, starting from a random orientation and position of the reactant molecules.…”

“…The AFIR method systematically explores the potential energy surface, starting from a random orientation and position of the reactant molecules. It has successfully been applied e.g., to the reaction between vinyl alcohol and formaldehyde, [5] HCo(CO)3-catalyzed hydroformylation, [6a] and the enzymatic mechanism of isopenicillin N synthase (IPNS), [6b] The method has recently been extended also to intramolecular pathways. [28] The detailed steps of the AFIR method can be found in reference [5] .…”

“…[5] This is a new computational algorithm that automatically locates stationary points of a bimolecular reaction without requiring any assumptions about the mechanism. With a stepwise application of the algorithm, complete reaction pathways can be calculated, and all possible products can be identified.…”

“…In previous applications of AFIR on other systems, a large number of pathways were found that had not been considered in manual explorations of the potential energy surfaces. [5][6] To explore how this approach can be used to analyse reactions between haloalkanes and radicals, the AFIR algorithm based on accurate Gaussian-4 (G4) theory, [7] has been applied to the reactions between ground state ( 2 Σ + ) cyano radicals (CN) and four different halomethanes (CH3Cl, CF3Cl, CH3Br, and CF3Br). Chloromethane, CH3Cl, is the most abundant organohalogen in the atmosphere and large amounts are produced by photoreactions between chlorine in ocean water and biomass from marine algea.…”

Analyses of bifurcation of reaction pathways on a global reaction route map: A case study of gold cluster Au5

“…Further details of the ADDF method are described in recent reviews. 5,6 Moreover, Maeda and Morokuma developed a new methodology to locate a TS geometry for A + B type reactions, named as artificial force induced reaction (AFIR), 7 which has made possible applications of GRRM more extensively. In 2014, the target of AFIR is extended to finding TSs of intramolecular reactions.…”