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Quantum Dynamics and Control of Surface Ultra-fast Processes

表面超快过程的量子动力学和控制

基本信息

批准号：
16072206
负责人：
YAMASHITA Koichi
金额：
$ 16.77万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research on Priority Areas
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2006
项目状态：
已结题

项目摘要

Photochemistry on Metal Surfaces: To understand photochemical reactions on surfaces, electronic excitation mechanisms should be specified, and it is well known that the substrate-mediated (indirect) excitation occurs in the majority of reactions on metal surfaces. We have developed a new theoretical method to calculate photon energy dependence of reaction probability triggered by substrate-mediated excitation using Nonequilibrium Green's function (NEGF) theory. We have performed DFT calculations to obtain the dimer adsorption structure and calculated the probability of photodesorption based on our NEGF theory. We have found that while the photoactive species is the NO dimer, a suitable resonant orbital is only one, and this single resonance is enough to reproduce the experimental data.A NEGF approach to interfacial electronic quantum transport: To model electron transport through a molecular junction, we propose an efficient method using an ab initio self-consistent NEGF combined with density functional theory. We have adopted a model close to the extended molecule approach, due to its flexibility, but have improved on the problems relating to molecule-surface couplings and the long-range potential via a systematic procedure for the same ab initio level as that of the Green's function. The resulting algorithm involves three main steps: (i) construction of the embedding potential; (ii) perturbation expansion of the Green's function in the molecular orbital basis; and (iii) truncation of the molecular orbital space by separating it into inactive, active, and virtual spaces. The algorithm is suitable for application to large molecular systems.

金属表面的光化学：为了理解表面上的光化学反应，应该指定电子激发机制，并且众所周知，在金属表面上的大多数反应中发生衬底介导的（间接）激发。本文利用非平衡绿色函数（NEGF）理论发展了一种新的理论方法来计算由底物介导激发引发的反应几率与光子能量的关系。我们已经进行了DFT计算，以获得二聚体的吸附结构和计算的光脱附的概率基于我们的NEGF理论。我们发现，当光活性物质为NO二聚体时，合适的共振轨道只有一个，这一单个共振轨道足以重现实验数据。NEGF方法研究界面电子量子输运：为了模拟电子通过分子结的输运，我们提出了一种有效的方法，将从头算自洽NEGF方法与密度泛函理论相结合。我们已经通过了一个模型接近的扩展分子的方法，由于其灵活性，但已通过一个系统的程序，为相同的从头算水平的绿色的功能，改善了有关的问题，分子表面的耦合和长程电位。由此产生的算法包括三个主要步骤：（一）建设的嵌入潜力;（二）微扰扩展的绿色的功能在分子轨道的基础上;和（iii）截断的分子轨道空间，将其分为非活性，活性和虚拟空间。该算法适用于大分子体系。