Large-curvature tunneling approximation

D. K. Bondi, J. N. L. Connor, B. C. Garrett, and D. G. Truhlar, Test of variational transition state theory with a large-curvature tunneling approximation against accurate quantal reaction probabilities and rate coefficients for three collinear reactions with large reaction-path curvature Cl + HC1, Cl + DC1, and Cl + MuCl, 7. Chem. Phys. 78 5981 (1983). 

Application of the Large-Curvature Tunneling Approximation to Polyatomic Molecules Abstraction of H or D by Methyl Radical. 

Test of Variational Transition State Theory with a Large-Curvature Tunneling Approximation Against Accurate Quantal Reaction ProbabiUties and Rate Coefficients for Three Collinear Reactions with Large Reaction-Path Curvature Atomic Chlorine -I- Hydrogen Chloride, Atomic Chlorine + Deuterium Chloride, and Atomic Chlorine + MuCl. 

When 2Qpv/cob < 1, we are in the fast-flip , or sudden approximation , or corner-cutting , or large curvature limit, where the reaction coordinate follows theMEP, but before it reaches the saddle point it tunnels along the s coordinate in a time that is short compared to the timescale of the Q vibration. 

Most recently, Truhlar, Garrett, and co-workers employ a combination of various small-curvature SAG and large-curvature (straight-line tunneling) approximations [106,110,124,154,155]. 

Section 2 also includes a brief review of the large-curvature and least-action tunneling approximations with emphasis on delineating the regions of the PES required for such calculations. 

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