Intra and intermolecular energy transfer and solvent effecft in liquid phase thermal dissociation

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Thermal dissociation reaction into polyatomic molecules N2O4=2NO2 on the ground state no-barrier potential energy surface was studied by classical molecular dynamics simulations on the work station set up by this research fund. A phase space surface E_T=V_<eff> (R_l) <approximately equal>0 is identified as the transition state (TS), where E_T is the sum of the potential and kinetic energies of interfragment motion and V_<effK> (R_l) is the orbital angular momentum dependent effective barrier. By dividing the motion of the system into fragments' vibratoinal (V), rotational (R), and interfragment (T) modes, where the T mode is composed of translational (TT) and orbital (TL) modes, a scheme of reactive energy transfer for fragmentation is presented. The present energy condition for the TS is in accord with the one of phase space theory. Dissociation is found to occur by energy redistribution among T-R-V modes followed by the one among TT-TL-R modes, which determine the product vibrational and rotational distributions, respectively. This scheme supports separate statistical ensemble method in reproducing the nascent distributions from unimolecular photofragmentation at excess energies above the vibrational threshold.