Tunneling effect in 1,5 H-migration of a prototypical •OOQOOH

Propane is the smallest molecule that can serve as a model of the chemistry of diesel autoignition. Diesel autoignition requires H-migration reactions of the type (OOCH2)-O-center dot CH2 CH2 OOH -> HOOCH2 CH2 (CHOOH)-H-center dot. Previous studies of this type of H-migration reaction accounted for tunneling (through-barrier processes) using 1-D models of the reaction coordinate, namely, the Eckart or Wigner approximations. Here we present the first study to use multi-dimensional approaches, specifically, small- and large-curvature tunneling, to treat through-barrier processes. Calculations are carried out using the POLYRATE program and make use of the M05-2X/6-31+G(d,p) level of theory. (C) 2016 Elsevier B.V. All rights reserved.