Vibrational Mode Selectivity in the Unimolecular Decomposition of CH2NNO2.
Abstract
Vibrational mode selectivity has been investigated for the unimolecular decomposition of methylene nitramine (MN), CH2NNO2, by using classical trajectories computed on a (previously reported) potential-energy surface (PES) that is based on ab initio results. The PES allows for the two known primary decomposition pathways: (I)N-N bond scission to form H2CN and NO2 and (11) concerted molecular elimination giving HONO and HCN. Rates were computed for 57.7 kcalAnol above the zero-point energy for initial conditions corresponding to overtone excitations of each of the 15 normal modes. One calculation was done at this energy with initial conditions corresponding to a microcanonical (statistical) distribution in which the energy was randomly distributed among all of the vibrational modes. Comparisons of the mode selective results with this statistical rate show that there is substantial enhancement of the decomposition rates for the two reactions for excitation of three of the normal modes. Excitation of the other 12 modes yielded rates in accord with the statistical rates for the two reactions. The results show that projection of a vibrational mode onto the reaction coordinate is necessary for mode selective reaction, but is not sufficient since energy transfer into the reaction coordinate must compete with energy flow to other modes that do not project onto (that is, are uncoupled from) the reaction coordinates.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1995
- Accession Number
- ADA294300
Entities
People
- Betsy M. Rice
- Donald L. Thompson
- John Grosh
Organizations
- United States Army Research Laboratory