Tremblay Jean Christophe, Blanco-Rey María
Institute for Chemistry and Biochemistry, Freie Universität Berlin, Takustr. 3, 14195 Berlin, Germany.
Phys Chem Chem Phys. 2015 Jun 7;17(21):13973-83. doi: 10.1039/c5cp00663e. Epub 2015 May 7.
In this contribution, we provide a detailed dynamical analysis of the interfacial hydrogen migration mediated by scanning tunneling microscopy (STM). Contributions from the STM-current and from the non-adiabatic couplings are taken into account using only first principle models. The slight asymmetry of the tunnelling rates with respect to the potential bias sign inferred from experimental observations is reproduced by weighting the contributions of the metal acceptor-donor states for the propagation of the impinging electrons. The quasi-thermal inelastic collision mechanism is treated perturbatively. The influence of hydrogen pre-coverage is also investigated using new potential energy surfaces obtained from periodic density functional theory calculations. Fully quantum dynamical simulations of the system evolution are performed by solving the Pauli master equation, providing insight into the reaction mechanism of STM manipulation of subsurface hydrogens. It is observed that the hydrogen impurity favors resurfacing over occupation of the bulk and subsurface sites whenever possible. The present simulations give strong indication that the experimentally observed protuberances after STM-excitation are due to hydrogen accumulating in the vicinity of the surface.
在本论文中，我们对扫描隧道显微镜（STM）介导的界面氢迁移进行了详细的动力学分析。仅使用第一性原理模型来考虑STM电流和非绝热耦合的贡献。通过对金属受体 - 供体状态对入射电子传播的贡献进行加权，再现了从实验观察推断出的隧穿速率相对于势偏压符号的轻微不对称性。准热非弹性碰撞机制采用微扰方法处理。还使用从周期性密度泛函理论计算获得的新势能面研究了氢预覆盖的影响。通过求解泡利主方程对系统演化进行全量子动力学模拟，深入了解了STM对亚表面氢的操纵反应机制。观察到氢杂质在可能的情况下更倾向于重新出现在表面而非占据体相和亚表面位置。目前的模拟有力地表明，STM激发后实验观察到的突起是由于氢在表面附近积累所致。
