Ab Initio Chemical Kinetics: Converged Quantal Reaction Rate Constants for the D + H2 System

Three-dimensional time-dependent quantum wave packet calculation for the O( 1 D)ϩHBr reaction has been carried out using an accurate ab initio global potential energy surface ͓K. A. Peterson, J. Chem. Phys. 113, 4598 ͑2000͔͒. The calculations show that the initial state-selected reaction probabilities are dominated by resonance structures, and the lifetime of the resonance is generally in the subpicosecond time scale. The energy dependence of the reaction cross section is computed, which manifests still resonance structures, and is a decreasing function of the translational energy. The thermal rate constants are also computed, which are nearly independent on the temperature. The calculation results are discussed and compared to similar reaction with deep well.

Section: Resultsmentioning

confidence: 99%

Section: B Quantum Calculationmentioning

confidence: 99%

Quantum scattering calculation of the O(1D)+HBr reaction

Tang

Chen

et al. 2004

“…[39][40][41] Figure 7 shows the calculated results, along with the QCT results and the experimental result. The quantum results shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…where k v 0 j 0 is the wave number corresponding to the initial state at fixed collision energy E. The reaction rate constant can be calculated by using the uniform version 39,40 of the J-shifting approximation. 41 By assuming a Maxwell-Boltzmann distribution over the translational energy, the initial state-selected thermal rate constant in the uniform J-shifting scheme is given by…”

Section: Theorymentioning

confidence: 99%

Accurate quantum mechanical calculation for the N+OH reaction

Chen

Tang

Han

et al. 2003

Accurate three-dimensional time-dependent quantum wave packet calculations for the NϩOH reaction on the 3 AЉ potential energy surface ͓Guadagnini, Schatz, and Walch, J. Chem. Phys. 102, 774 ͑1995͔͒ have been carried out. The calculations show for the first time that the initial state-selected reaction probabilities are dominated by resonance structures, and the lifetime of the resonance is generally in the subpicosecond time scale. The calculated reaction cross sections indicate that they are a decreasing function of the translational energy, which is in agreement qualitatively with the quasiclassical trajectory calculations. The rate constants obtained from the quantum mechanical calculations are consistent with the quasiclassical trajectory results and the experimental measurements.

“…Recently there have been several exact 16,37 and approximate 38 calculations of the thermal rate constant for the DϩH 2 reaction. These provide the opportunity for us to test our method on a full three-dimensional system.…”

Section: B Collinear H؉hmentioning

confidence: 99%

On the ‘‘direct’’ calculation of thermal rate constants

Thompson

Miller

1995

We present a new approach for the direct ͑and correct͒ calculation of thermal rate constants k(T) ͑''direct'' meaning that one avoids having to solve the state-to-state reactive scattering problem, and ''correct'' meaning that the method contains no inherent approximations͒. The rate constant is obtained from the long time limit of the flux-position correlation function, C f ,s (t), whose calculation is made efficient by taking advantage of the low rank of the flux operator. Specifically, the trace required to obtain C f ,s (t) is evaluated by a Lanczos iteration procedure which calculates only the nonzero eigenvalues. The propagation in complex time, t c ϭtϪiប␤/2, is carried out using a Chebychev expansion. This method is seen to be both accurate and efficient by application to the Eckart barrier, the collinear HϩH 2 reaction, and the three-dimensional DϩH 2 ͑Jϭ0͒ reaction.