Ab initio description of non-adiabatic effects in dissociative adsorption at surfaces

表面解离吸附非绝热效应的从头算

• 批准号: 5452819
• 负责人: Professor Dr. Karsten Reuter
• 金额: --
• 依托单位: Institut für Theoretische Chemie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2005
• 资助国家: 德国
• 起止时间: 2004-12-31 至 2011-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/5452819?language=en
• 关键词: Ab; initio; description; non; adiabatic

A predictive materials science modeling based on microscopic understanding requires a thorough knowledge of all underlying elementary processes at the atomic scale. The (dissociative) adsorption of individual gas phase molecules at metal surfaces is such an elementary process that is of crucial relevance for any application involving surfaces exposed to realistic gas environments, with heterogeneous catalysis forming just one prominent example. Unfortunately, our present understanding of this fundamental process is even for a most simple, but ubiquitous diatomic molecule like 02 very shallow. Lacking reliable and resolved information about the interaction of an impinging molecule with the surface electronic structure (summarized in form of a socalled potential-energy surface (PES)), empirical theories have invoked controversial scenarios to account for experimentally accessible, integral kinetic quantities like the sticking probability at the surface. Among these scenarios is the frequently discussed role of non-adiabatic effects in the dissociation, i.e. a possible violation of the Born-Oppenheimer approximation and electron distributions that are not able to follow the nuclear motion instantaneously. Clarifying insight into this matter can only come from firstprinciples theories like density-functional theory (DFT), which involve a reliable, though approximate description of the electronic structure of the system. Based exclusively on the adiabatic DFT-PES, such theories have in the past been predominantly developed for H2 dissociation at metal surfaces, where non-adiabatic effects apparently play no role. Recent methodological developments have now also enabled the calculation of diabatic PESs within constrained DFT approaches. Correspondingly, we propose a first systematic investigation addressing the real importance of non-adiabatic effects in 02 dissociation. To unambiguously pin down the role played by these effects, this requires to concomitantly tackle a number of other, not yet fully understood issues like the required accuracy in the description of electron correlation or the influence of surface mobility. Focusing at the dynamics of 02 dissociation at a representative set of surfaces, the emerging trend picture over the periodic table is expected to contribute to a first comprehensive understanding of the (dissociative) adsorption of this most important molecule, that may also give some guidance on the dissociation of other widespread diatomics like N2, NO or CO.

基于显微镜理解的预测材料科学建模需要在原子量表上透彻了解所有基本过程。单个气相分子在金属表面上的（解离性）吸附是一个基本过程，对于任何涉及暴露于现实气体环境的表面的应用至关重要的相关性，而异质性催化仅形成一个突出的例子。不幸的是，我们目前对这个基本过程的理解甚至是一个最简单但无处不在的双原子分子，例如02非常浅。缺乏有关撞击分子与表面电子结构相互作用的可靠和解决的信息（以所谓的潜在能力表面（PES）的形式汇总，经验理论已经引起了有争议的场景，以说明实验上可访问的积分动力学数量，例如在表面上的粘贴可能性。在这些情况中，经常讨论非绝热作用在解离中的作用，即可能违反了未渗透性的近似值和无法立即遵循核运动的电子分布。澄清对此事的见解只能来自第一原理理论，例如密度功能理论（DFT），该理论涉及对系统电子结构的可靠但近似描述。这些理论仅基于绝热的DFT-PE，主要是为了在金属表面上的H2解离而开发的，在金属表面上，非绝热效应显然没有作用。现在，最近的方法论发展也能够计算受约束的DFT方法中的绝热伙伴。相应地，我们提出了第一个系统研究，该研究涉及02分离中非绝热效应的真正重要性。要明确地固定这些效果所起的作用，这需要同时解决许多其他问题，尚未完全理解的问题，例如描述电子相关性或表面迁移率的影响时所需的准确性。重点是在一组代表性的表面上分离的动力学，预计元素周期表上的新出现趋势图片将有助于首先全面地理解该最重要的分子（分离）吸附该最重要的分子，这也可能会为其他广泛的diotomics（如N2）等其他广泛的diotomics的解离，没有或co。