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

在本研究基金设立的工作台上，通过经典分子动力学模拟研究了N2O4=2NO2在基态无势垒位能面上的热解离反应。将E_T=V_<eff> (R_l) <近似等于>0的相空间表面确定为过渡态（TS），其中E_T为碎片间运动势能和动能之和，V_<effK> (R_l)为依赖轨道角动量的有效势垒。通过将系统的运动划分为碎片的振动(V)、旋转(R)和碎片间(T)模式，其中T模式由平移（TT）和轨道（TL）模式组成，提出了碎片反应能量传递方案。目前TS的能量条件符合相空间理论。发现解离发生在T-R-V模式之间的能量再分配，然后是TT-TL-R模式之间的能量再分配，这分别决定了产物的振动和旋转分布。该方案支持单独的统计系综方法在振动阈值以上的过剩能量下再现单分子光碎裂的新生分布。

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.