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A new full-dimensional potential energy surface for the title reaction has been constructed using the modified Shepard interpolation scheme. Energies and derivatives were calculated using the UCCSD(T) method with aug-cc-pVTZ and 6-311++G(3df,2pd) basis sets, respectively. A total number of 30,000 data points were selected from a huge number of molecular configurations sampled by trajectory method. Quantum dynamical calculations showed that the potential energy surface is well converged for the number of data points for collision energy up to 2.5 eV. Total reaction probabilities and integral cross sections were calculated on the present surface, as well as on the ZBB3 and EG-2008 surfaces for the title reaction. Satisfactory agreements were achieved between the present and the ZBB3 potential energy surfaces, indicating we are approaching the final stage to obtain a global potential energy surface of quantitative accuracy for this benchmark polyatomic system. Our calculations also showed that the EG-2008 surface is less accurate than the present and ZBB3 surfaces, particularly in high energy region.

Abstract: A six-dimensional state-to-state quantum dynamics study is carried out for the prototypical complex-formation OH+CO→H+CO2 reaction from the ground and two vibrationally excited initial states on the Lakin–Troya–Schatz–Harding potential energy surface for the total angular momentum J =0, using the multiple-step reactant–product decoupling method. With three heavy atoms and deep wells on the reaction path, the reaction represents a huge challenge for accurate quantum dynamics study. The effects of reagent vibrational excitation on product CO2 vibrational state distributions and product energy partition were investigated for reagents in the ground rotational state. It is found that the initial CO vibrational excitation essentially has the same effect on the product energy partition as the reagent translational excitation, while the initial OH excitation leads to slightly more internal energy in CO2. [Copyright &y& Elsevier]

A converged quantum wave packet study is presented for the unimolecular reaction HOOH → OH+OH induced by the fifth OH-overtone excitation employing an ab initio potential energy surface. All six internal vibrational degrees of freedom are explicitly represented in this simulation for total angular momentum zero. It is found that the decay of the survival probability and of the autocorrelation function is non-exponential and that the long time dynamics is likely due to the superposition of a number of resonance states. The simulated overtone spectrum and rotational product distribution is in good agreement with experimental measurements. It is concluded that: (1) the reaction dynamics is non-statistical on a 30 ps timescale, (2) the observed line width is roughly a factor of 1.7 larger than implied by the reactive lifetimes suggesting that a significant portion of the linewidth is due to intramolecular vibrational energy relaxation, and (3) the quantum reaction rate is suppressed by about a factor of two relative to its classical counterpart. [ABSTRACT FROM AUTHOR]