Laser-driven coupled electron-nuclear dynamics : Quantum mechanical simulation of molecular photodesorption from metal films
Laser-driven coupled electron-nuclear dynamics : Quantum mechanical simulation of molecular photodesorption from metal films
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激光驱动的电子核耦合动力学：金属薄膜分子光解吸的量子力学模拟
DOI：
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发表时间：
2005
期刊：
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通讯作者：
P. Saalfrank
中科院分区：
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作者：
T. Klamroth;D. Kröner;P. Saalfrank
本文报道了激光驱动的分子-表面系统的核-电子耦合动力学的动力学模拟。具体地说，研究了在所谓的饮食极限(由电子跃迁诱导的脱附)下，小分子(NO)从金属板(PT)上的激光脱附。激光脉冲对金属电子的激发、负离子共振的形成、随后的衰变以及分子的同时脱附，都是在一个量子力学模型中处理的。该模型基于Harris等人的早期理论[S.M.Harris，S.Holloway，和G.R.Darling，J.Chem。太棒了。102,8235(1995)]，根据该理论，原子核自由度与电子自由度耦合，两者都在单一的非Born-Oppenheimer势能面上传播。本报告的目的是(1)在概念上将该模型与常用的非绝热“多态”光解吸模型联系起来，(2)了解解吸机制的细节，(3)明确地解释激光脉冲，以及(4)研究作为金属膜厚度和激光参数函数的光解吸。作为一个重要的方法论方面，我们还提出了一个在问题适应的非绝热基础上传播波包的高效数值格式。
In this paper we report dynamical simulations of laser-driven, coupled nuclear-electron dynamics for a molecule-surface system. Specifically, the laser desorption of a small molecule (NO) from a metal slab (Pt) in the so-called DIET limit (Desorption Induced by Electronic Transitions), is studied. The excitation of the metal electrons by a laser pulse followed by the formation of a negative ion resonance, its subsequent decay, and the simultaneous desorption of the molecule are all treated within a single quantum mechanical model. This model is based on an earlier theory of Harris and others [S. M. Harris, S. Holloway, and G. R. Darling, J. Chem. Phys. 102, 8235 (1995)], according to which a nuclear degree of freedom is coupled to an electronic one, both propagated on a single non-Born-Oppenheimer potential energy surface. The goals of the present contribution are (i) to make a conceptual connection of this model to the frequently adopted nonadiabatic ``multi-state' models of photodesorption, (ii) to understand details of the desorption mechanism, (iii) to explicitly account for the laser pulse, and (iv) to study the photodesorption as a function of the thickness of the metal film, and the laser parameters. As an important methodological aspect we also present a highly efficient numerical scheme to propagate the wave packet in a problem-adapted diabatic basis.