Comparing electronic structure calculations for the ground state dissociation of vinoxy radicals

PHYS 602

Doran I G Bennett, doran@umd.edu, Department of Chemistry and Biochemistry, University of Maryland, 0107 Chemistry Building, University of Maryland, College Park, MD 20742-4454, Laurie J. Butler, L-Butler@uchicago.edu, Department of Chemistry, The University of Chicago, The James Franck Institute, 929 E. 57th Street, Chicago, IL 60637, and Hans-Joachim Werner, werner@theochem.uni-stuttgart.de, Institute for Theoretical Chemistry, University of Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany.
A previous study of the vinoxy radical has reported experimental branching ratios for the competing H-loss and CH3+CO reaction channels after formation of hot ground-state radicals. Differences of up to two orders of magnitude were reported between the experimental branching ratio and those predicted using statistical methods. Following two leads towards the surprising discrepancy in branching ratios, the barrier heights are investigated at multiple levels of theory and non-adiabatic coupling matrix elements (NACME) are calculated along the reaction paths. Agreement between our UCCSD(T) and MRCI+Q calculations lend support to the new predictions for the barrier heights while the small values of the NACME calculated corroborate the use of a single-state model for dissociation. A “worst-case” statistical model is found to differ from the experimental branching ratios by more than an order of magnitude, suggesting either non-statistical dissociation or an incorrect interpretation of the experimental results.
 

PHYS Poster Session - Computational Spectroscopy and Reaction Dynamics
7:30 PM-10:00 PM, Wednesday, April 9, 2008 Morial Convention Center -- Hall A, Poster

Division of Physical Chemistry

The 235th ACS National Meeting, New Orleans, LA, April 6-10, 2008