# Quantum Energy Flow and *trans*-Stilbene Photoisomerization: an Example of a
Non-RRKM Reaction^{†}

journal contribution

posted on 11.12.2003, 00:00 by David M. Leitner, Benjamin Levine, Jason Quenneville, Todd J. Martínez, Peter G. WolynesWe apply multireference ab initio quantum chemistry and microcanonical transition state (RRKM) theory
with quantum energy flow corrections from local random matrix theory (LRMT) to determine the kinetics of

*trans*-stilbene photoisomerization. With a single ab initio potential energy surface and*no*adjustable parameters, simultaneous agreement with experiment of the microcanonical isomerization rates for the*d*_{0},*d*_{2},*d*_{10}, and*d*_{12}isotopomers is obtained. We are also able to reproduce the pressure dependence of the thermal rate. Laser cooling effects on the isomerization rate are calculated and found to be quite small. The S_{1}/S_{2}energy gap at the transition state is found to be quite large (0.86 eV), suggesting that nonadiabatic effects are negligible. Using the ab initio results in a simple RRKM theory without corrections for finite quantum energy flow does*not*lead to agreement with experiment. We conclude that non-RRKM effects are essential to understand photoisomerization of*trans*-stilbene and that these can be predicted using LRMT.## Read the peer-reviewed publication

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## Keywords

pressure dependencequantum energy flow correctionsquantum energy flowmultireference ab initio quantum chemistrystilbene photoisomerizationnonadiabatic effectslaser cooling effectsLRMTexperimentRRKM theorytransition statemicrocanonical transition stateab initio results12 isotopomersquantum Energy Flowisomerization ratematrix theoryab initioenergy surfacemicrocanonical isomerization rates

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## Read the peer-reviewed publication

## Categories

## Keywords

pressure dependencequantum energy flow correctionsquantum energy flowmultireference ab initio quantum chemistrystilbene photoisomerizationnonadiabatic effectslaser cooling effectsLRMTexperimentRRKM theorytransition statemicrocanonical transition stateab initio results12 isotopomersquantum Energy Flowisomerization ratematrix theoryab initioenergy surfacemicrocanonical isomerization rates