Wavepacket dynamics of ultrafast reactions with relaxation

从理论上研究了振动弛豫对Pt（111）表面NO光解吸动力学的影响。虽然这一系统在以前的许多工作中已经被研究过，但是由于金属中电子-空穴对的相互作用而导致的NO拉伸振动的弛豫并没有被包括在传统的模型中。虽然吸附在金属表面的双原子分子的第一激发振动态的弛豫寿命一般在0.1- 1ps范围内，但NO的解吸动力学在1ps左右完成。因此，可以认为在解吸过程中，振动弛豫会影响这种拉伸模式的振动状态。我们用密度矩阵的时间传播描述了解吸动力学。采用类似redfeld的模型包括了振动松弛的影响。我们还研究了用从头算方法计算动力学参数的有效性。得到了解吸后NO分子的解吸概率、平均平动能、振动态分布等物理上合理的结果。

The effect of vibrational relaxation on the photodesorption dynamics of NO from a Pt(111) surface has been investigated theoretically. Although this system has been studied in many previous works, the relaxation of NO stretching vibration due to the interaction with electron-hole pairs in metals has not been included in conventional models. Although the relaxation lifetimes of the first-excited vibrational state of diatomic molecules adsorbed on metal surfaces are generally in the range 0.1-1 ps, the desorption dynamics of NO complete in about 1 ps. Therefore, it is considered that the vibrational relaxation can influence the vibrational state of this stretching mode during the desorption process. We described the desorption dynamics by using the time propagation of the density matrix. The effects of vibrational relaxation were included by using a Redfleld-like model. We also investigated the validity of the parameters for dynamical calculations by ab initio methods. As a result, we obtained physically reasonable results for the desorption probability, the mean translational energy, and the vibrational state distribution for the desorbed NO molecules.