Intramolecular energy transfer and cis-trans isomerization in HONO

Classical trajectories have been used to investigate cis-trans isomerization and intramolecular energy transfer in nitrous acid. The influence of various initial normal mode excitations has been investigated. Power spectra have been used to examine the intramolecular dynamics. The rate of cis-trans conversion is strongly dependent on the site of initial excitation. The rates for cis-trans isomerization is significantly higher than those for trans-cis. The results show that the OH stretching mode is only weakly coupled to the other modes. Energy transfer out of excited states of the OH mode is slow and preferential partitioning of energy into that mode leads to a reduced rate of isomerization, while excitation of other modes gives rate enhancement. The HON bend interacts with the torsion more strongly than do the other modes.