Role of electronic friction during the scattering of vibrationally excited nitric oxide molecules from Au(111)
Role of electronic friction during the scattering of vibrationally excited nitric oxide molecules from Au(111)
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DOI：
10.1103/physrevb.82.075404
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发表时间：
2010-08
影响因子：
3.7
通讯作者：
S. Monturet;P. Saalfrank
中科院分区：
文献类型：
--
作者：
S. Monturet;P. Saalfrank
不久前，人们观察到，振动高度激发的 $\text{NO}(v)$ 分子（具有典型的振动量子数 $v\ensuremath{\approx}15$）在从 Au(111) 表面散射时会损失大量振动能量 [H. Huang, C. Rettner, D. Auerbach, and A. Wodtke, Science 290, 111 (2000)]。这被解释为由于振动电子耦合而导致玻恩-奥本海默近似崩溃的标志。有人认为，这个过程不能基于单量子跃迁来理解，单量子跃迁是基于弱振动电子耦合的微扰处理的“电子摩擦”模型的典型特征。相反，根据最近涉及多个势能表面和模型哈密顿量的经典表面跳跃计算，需要具有强非绝热效应的多量子跃迁特征[N. Shenvi、S. Roy 和 J. C. Tully，科学 326, 829 (2009)]。在这里，我们通过使用降维中的完全量子力学、无参数第一原理理论来解决 $\text{NO}@\text{Au}(111)$ 电子摩擦的重要性和大小。进行周期性密度泛函理论计算，以获得沿解吸和 NO 振动坐标的基态势能表面，以及由于振动电子耦合而得到的坐标解析的有限 NO 振动寿命。使用该输入，在耦合通道密度矩阵方法的框架中通过开放系统密度矩阵理论对散射事件进行建模，该方法允许包含散射 NO 分子的能量弛豫。研究发现，至少在这个模型中，电子摩擦解释了观察到的金中 NO 散射的振动失活。
Some time ago, it has been observed that vibrationally highly excited $\text{NO}(v)$ molecules (with typical vibrational quantum numbers $v\ensuremath{\approx}15$) lose substantial amounts of vibrational energy when scattering off a Au(111) surface [H. Huang, C. Rettner, D. Auerbach, and A. Wodtke, Science 290, 111 (2000)]. This has been interpreted as a sign for the breakdown of the Born-Oppenheimer approximation due to vibration-electron coupling. It has been argued that this process cannot be understood on the basis of single-quantum transitions which are typical for ``electronic friction'' models based on a perturbative treatment of weak vibration-electron couplings. Rather, multiple-quanta transitions characteristic for strong nonadiabatic effects are needed according to recent classical surface hopping calculations involving multiple potential-energy surfaces and model Hamiltonians [N. Shenvi, S. Roy, and J. C. Tully, Science 326, 829 (2009)]. Here we address the importance and magnitude of electronic friction for $\text{NO}@\text{Au}(111)$ by using fully quantum-mechanical, parameter-free first-principles theories in reduced dimensions. Periodic density-functional theory calculations are performed to obtain a ground-state potential-energy surface along the desorption and NO-vibration coordinates, and coordinate-resolved, finite NO vibrational lifetimes due to vibration-electron coupling. Using this input, the scattering event is modeled by open-system density-matrix theory in the frame of the coupled-channel-density-matrix method, which allows for the inclusion of energy relaxation of the scattering NO molecules. It is found that within this model at least, electronic friction accounts for the observed vibrational deactivation of NO scattering from gold.