Artificial Force Induced Reaction (AFIR) Method for Exploring Quantum Chemical Potential Energy Surfaces.

TLDR: The AFIR method is one of the automated reaction-path search methods developed by the authors, and has been applied extensively to a variety of chemical reactions, such as organocatalysis, organometallic catalysis, and photoreactions.

Abstract: In this account, a technical overview of the artificial force induced reaction (AFIR) method is presented. The AFIR method is one of the automated reaction-path search methods developed by the authors, and has been applied extensively to a variety of chemical reactions, such as organocatalysis, organometallic catalysis, and photoreactions. There are two modes in the AFIR method, i.e., a multicomponent mode and a single-component mode. The former has been applied to bimolecular and multicomponent reactions and the latter to unimolecular isomerization and dissociation reactions. Five numerical examples are presented for an Aldol reaction, a Claisen rearrangement, a Co-catalyzed hydroformylation, a fullerene structure search, and a nonradiative decay path search in an electronically excited naphthalene molecule. Finally, possible applications of the AFIR method are discussed.

Figures

Fig. 9. The correlation between the fluorescence quantum yields measured in cyclohexane,121 and the energy difference, ELowest-MECI − EFC (cross marks). Each PAH is indicated with the structure and name of the PAH. Reproduced from Ref. 74 with permission from the Royal Society of Chemistry.

Fig. 6. Reaction pathways obtained by MC- and SC-AFIR for the last part of Co-catalyzed hydroformylation. TSx/y is a transition state connecting MINx and MINy

Fig. 1. A diatomic potential curve E(rAB) between atoms A and B (see the black curve) and the corresponding AFIR function E(rAB) + αrAB (see the blue curve). rAB is the distance between A and B, and α is a constant parameter.

Fig. 7. Initial random structure, initial local minimum structure obtained by optimization of the random structure, and the final structure seen in the 10 independent stochastic SC-AFIR searches. The number of gradients computed in each step ng is shown below arrows. Electronic energy relative to Buckminsterfullerene is shown below each structure.

Fig. 4. Reaction pathways obtained by MC- and SC-AFIR for the initial part of Co-catalyzed hydroformylation. TSx/y is a transition state connecting MINx and MINy in this figure. Gibbs free energy and electronic energy in parentheses relative to separately optimized reactants are shown in kJ/mol. DC stands for dissociation channel: DC1 is HCo(CO)3 + CO at 0.0 (0.0) kJ/mol, DC2 is MIN7 + CO at −45.1 (−106.1) kJ/mol, and DC3 is MIN6 + C2H4 at −115.5 (−171.5) kJ/mol.

Fig. 3. Reaction pathways obtained by SC-AFIR for the unimolecular reaction of allyl vinyl ether. TSx/y is a transition state connecting MINx and MINy in this figure. Gibbs free energy and electronic energy in parentheses relative to separately optimized reactants are shown in kJ/mol. Structures missed by the without-Hessian algorithm are indicated by *.