Calculation of state-to-state differential and integral cross sections for atom-diatom reactions with transition-state wave packets

Abstract

A recently proposed transition-state wave packet method [R. Welsch, F. Huarte-Larrañaga, and U. Manthe, J. Chem. Phys. 136, 064117 (2012)] provides an efficient and intuitive framework to study reactive quantum scattering at the state-to-state level. It propagates a few transition-state wave packets, defined by the eigenfunctions of the low-rank thermal flux operator located near the transition state, into the asymptotic regions of the reactant and product arrangement channels separately using the corresponding Jacobi coordinates. The entire S-matrix can then be assembled from the corresponding flux-flux cross-correlation functions for all arrangement channels. Since the transition-state wave packets can be defined in a relatively small region, its transformation into either the reactant or product Jacobi coordinates is accurate and efficient. Furthermore, the grid/basis for the propagation, including the maximum helicity quantum number K, is much smaller than that required in conventional wave packet treatments of state-to-state reactive scattering. This approach is implemented for atom-diatom reactions using a time-dependent wave packet method and applied to the H + D2 reaction with all partial waves. Excellent agreement with benchmark integral and differential cross sections is achieved.

Communication: State-to-state dynamics of the Cl + H2O → HCl + OH reaction: Energy flow into reaction coordinate and transition-state control of product energy disposal

“…[24][25][26][27][28] The state-to-state quantum dynamical calculations reported here are made possible using a transition-state wave packet (TSWP) method recently proposed by Manthe and coworkers, [29][30][31] which is an extension of Miller's quantum transition-state theory. 32,33 Our implementation of this method has been discussed in detail elsewhere, 16,34 so only a brief outline is given here. Specifically, the initial TSWPs are defined in the transition-state region as the eigenstates (| f n T ⟩) of the thermal flux operator:…”

Rigorous close-coupling quantum dynamics calculation of thermal rate constants for the water formation reaction of H2 + OH on a high-level PES

“…36,37 The quantum transition state concept has been proven as the most efficient method to treat the reaction dynamics of polyatomic systems rigorously. 22,35,[38][39][40][41][42][43][44][45][46][47] The quantum transition state concept is particularly efficient for the calculation of thermal rate constants. In the quantum transition state concept, the eigenstates of the thermal flux operator, which represent the relevant vibrational states of the activated complex, are employed.…”

Low‐Temperature Thermal Rate Constants for the Water Formation Reaction H2+OH from Rigorous Quantum Dynamics Calculations

“…Accurate and efficient full‐dimensional TRC calculations often employ the quantum transition‐state concept as well as the multi‐configurational time‐dependent Hartree (MCTDH) approach . The quantum transition‐state concept has been shown to be the most efficient method to rigorously treat the reaction dynamics of polyatomic systems . The eigenstates of the thermal flux operator, which can be interpreted as the vibrational states of the activated complex, are calculated in the transition‐state region.…”