硝基甲烷振动能量弛豫的集体模型

用分子动力学方法结合Dlott等人提出的"门槛模"理论研究集体相互作用下硝基甲烷振动能量弛豫过程.其中振动冷却过程与实验符合的很好.在振动激发过程的分子动力学模拟中观测到与实验一致的基频频移现象.用分子动力学方法从微观上详细地描述出分子"门槛模"振动激发过程.研究表明,在高温高压作用下,集体作用效应对多原子振动激发具有不可忽视的作用,能量传递过程中除了基频的作用外,强烈的非线性相互作用引起的振动模泛频也携带有大量的振动能,这些泛频也对分子振动能量传递产生重要影响.

Vibrational Energy Relaxation of Nitromethane in Collective Model

We study vibrational energy relaxation of a "doorway model" (including the scissor,wagging and rocking mode) for nitromethane by molecular dynamics in collective interaction model.Relaxation time in vibrational cooling(VC) process agrees with experimental results.Frequency shifts for modes are consistent with experimental measurements at high-pressure in vibrational pumping(VP) process.VP process of nitromethane is observed in MD simulation in detail.It is shown that collective effects are important in vibrational energy relaxation at high-pressure and high-temperature,and energy of overtone-frequency as well as fundamental frequency of the modes must be taken into account in translational-vibrational energy transfer.