Institut fur Theoretische Physik und Astrophysik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany.
Phys Rev Lett. 2014 Jan 31;112(4):043201. doi: 10.1103/PhysRevLett.112.043201. Epub 2014 Jan 29.
In this Letter, ab initio molecular dynamics simulations based on time-dependent density functional theory for the electrons and Ehrenfest dynamics for the nuclei are reported that detail the interaction of a vibrating HCl molecule with an Al(111) substrate. The mechanism responsible for the strong electron-hole-pair (EHP)-vibrational coupling in case of highly vibrationally excited molecules is traced back to a large eigenenergy shift of the spz*-like antibonding HCl lowest unoccupied molecular orbital with the bond length. As a consequence of this mechanism, the electronic excitation spectra turn out to be highly asymmetric. The simulations suggest an explanation of how to reconcile a strong EHP-vibrational coupling in case of highly vibrationally excited molecules with the small, but clearly evident, electronic contribution to the v=0 → v=1 vibrational excitation observed experimentally during the scattering of HCl molecules at a hot Au surface by Ran et al. [Phys. Rev. Lett. 98 237601 (2007)].
在这封信件中，报告了基于含时密度泛函理论的电子的从头算分子动力学模拟和原子核的 Ehrenfest 动力学，详细描述了振动 HCl 分子与 Al(111) 衬底的相互作用。对于高度振动激发的分子，导致强电子空穴对 (EHP)-振动耦合的机制可以追溯到 spz*-样反键 HCl 最低未占据分子轨道与键长的大本征能量位移。由于这个机制，电子激发光谱呈现出高度不对称性。这些模拟表明了如何解释在高度振动激发的分子中存在强 EHP-振动耦合的同时，如何与 Ran 等人在 Au 表面上散射 HCl 分子时实验观测到的电子对 v=0 → v=1 振动激发的小但明显的贡献相协调的问题。[Phys. Rev. Lett. 98 237601 (2007)]。
