QRRK with Master Equation

Multifrequency Quantum Rice-Ramsperger-Kassel (QRRK) is a method used to predict temperature and pressure-dependent rate coefficients for complex bimolecular chemical activation and unimolecular dissociation reactions. Both the forward and reverse paths are included for adducts, but product formation is not reversible in the analysis. A three-frequency version of QRRK theory is developed coupled with a Master Equation model to account for collisional deactivation (fall-off). The QRRK/Master Equation analysis is described thoroughly by Chang et al. [62, 63]. 

Molecular density-of-state functions are constructed through direct convolution of single frequency density functions. The functions corresponding to each reduced frequency are explicitly convoluted into a relative density of states, which is normalized by the partition function p(E)/Q). The inclusion of one external rotation, corresponding to the symmetric top, is incorporated into the calculations by convoluting the vibration density function with the proper rotational density function. 

Rate constant results from QRRK/Master Equation analysis are shown to accurately reproduce (model) experimental data on several complex systems. They also provide a reasonable method to estimate rate constants for numerical integration codes by which the effects of temperature and pressure can be evaluated in complex reaction systems. 

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Multi channel, multi-frequency Quantum RRK calculations are performed for k(E) with master equation analysis for falloff on the chemical activated phenyl peroxy radical [PhOO ] and the intermediates (isomers) in this complex reaction system. This provides an evaluation of the rate constants for the formation of stabilized adducts or reaction products as a function of pressure and temperature. The bi-molecular chemical activated reaction of Phenyl + O2 system is carried out using the CHEMASTER program and incorporates all adducts and product channels illustrated. QRRK with Master equation analysis is used for unimolelcular dissociation of each adduct, but only isomeration to parallel, adjacent products / wells is included in the dissociation of stabilized intermediates. The input file for the phenyl + O2 reaction system is given in the appendix F. 

Scheme FI Input file for QRRK analysis with master equation analysis for Fall-off...

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