Department of Aerospace Engineering, University of Michigan, 1320 Beal Ave., Ann Arbor, Michigan 48108, USA.
J Chem Phys. 2018 Feb 28;148(8):084309. doi: 10.1063/1.5007069.
Simulation of vibrational energy transfer and dissociation in O-N collisions is conducted using the quasi-classical trajectory method on an ab initio potential energy surface. Vibrationally resolved rate coefficients are obtained in a high-temperature region between 8000 and 20 000 K by means of the cost-efficient classical trajectory propagation method. A system of master equations is constructed using the new dataset in order to simulate thermal and chemical nonequilibrium observed in shock flows. The O relaxation time derived from a solution of the master equations is in good agreement with the Millikan and White correlation at lower temperatures with an increasing discrepancy toward the translational temperature of 20 000 K. At the same time, the N master equation relaxation time is similar to that derived under the assumption of a two-state system. The effect of vibrational-vibrational energy transfer appears to be crucial for N relaxation and dissociation. Thermal equilibrium and quasi-steady state dissociation rate coefficients in O-N heat bath are reported.
使用从头算势能面的准经典轨迹方法对 O-N 碰撞中的振动能量转移和离解进行了模拟。通过高效的经典轨迹传播方法，在 8000 到 20000 K 的高温区域获得了振动分辨率的速率系数。为了模拟激波流中观察到的热和化学非平衡，使用新数据集构建了一组主方程。从主方程的解中得出的 O 弛豫时间与较低温度下的密立根和怀特相关关系吻合良好，而向 20000 K 的平移温度的差异逐渐增大。同时，N 主方程弛豫时间与假设的两态系统得出的弛豫时间相似。振动-振动能量转移的影响似乎对 N 的弛豫和离解至关重要。报告了 O-N 热浴中的热平衡和准稳态离解速率系数。
