正确描述与扩展(金属)表面接触的分子的电子交换和相关效应是第一性原理建模的一项具有挑战性的任务。在这项工作中,我们证明了集体范德华色散效应的重要性,超越了成对近似的有机-无机系统的原子,分子和纳米结构吸附在金属上的例子。我们在密度泛函理论的背景下使用最近开发的多体色散(MBD)方法[Phys. Rev. Lett. 108,236402(2012); J.Chem.Phys.140,18 A508(2014)],并评估其正确描述吸附物在金属表面上的结合的能力。我们简要回顾MBD方法,并强调其相似之处量子化学方法的电子相关的准粒子图片。特别地,我们研究了氙、3,4,9,10-二萘嵌苯四羧酸(PTCDA)和吸附在Ag(111)表面上的石墨烯片的结合性质。考虑到MBD效应,我们能够描述各向异性极化率张量的变化,改善吸附质振动的描述,并正确捕获吸附质-表面相互作用筛选。与其他方法和实验的比较表明,包含MBD效应通过减少通常在成对添加剂分散校正方法中发现的过结合来改善吸附能和几何形状。
英文摘要:
A correct description of electronic exchange and correlation effects for molecules in contact with extended (metal) surfaces is a challenging task for first-principles modeling. In this work we demonstrate the importance of collective van der Waals dispersion effects beyond the pairwise approximation for organic--inorganic systems on the example of atoms, molecules, and nanostructures adsorbed on metals. We use the recently developed many-body dispersion (MBD) approach in the context of density-functional theory [Phys. Rev. Lett. 108, 236402 (2012); J. Chem. Phys. 140, 18A508 (2014)] and assess its ability to correctly describe the binding of adsorbates on metal surfaces. We briefly review the MBD method and highlight its similarities to quantum-chemical approaches to electron correlation in a quasiparticle picture. In particular, we study the binding properties of xenon, 3,4,9,10-perylene-tetracarboxylic acid (PTCDA), and a graphene sheet adsorbed on the Ag(111) surface. Accounting for MBD effects we are able to describe changes in the anisotropic polarizability tensor, improve the description of adsorbate vibrations, and correctly capture the adsorbate--surface interaction screening. Comparison to other methods and experiment reveals that inclusion of MBD effects improves adsorption energies and geometries, by reducing the overbinding typically found in pairwise additive dispersion-correction approaches.
The adsorption of metal atoms on nanostructures, such as graphene and nanotubes, plays an important role in catalysis, electronic doping, and tuning material properties. Quantum chemical calculations permit the investigation of this process to discover desirable interactions and obtain mechanistic insights into adsorbate behavior, of which the binding strength is a central quantity. However, binding strengths vary widely in the literature, even when using almost identical computational methods. To address this issue, we investigate the adsorption of a variety of metals onto graphene, carbon na…
Interfacial charge rearrangement and intermolecular interactions: Density-functional theory study of free-base porphine adsorbed on Ag(111) and Cu(111)
The electronic structure of clean and adsorbate-covered Bi2Se3: an angle-resolved photoemission study
角分辨光电子能谱学用于详细研究的电子结构的拓扑绝缘体Bi 2 Se 3。名义化学计量和钙掺杂的样品进行了研究。原始表面显示了体带隙中的拓扑表面态。随着时间的推移,狄拉克点移动到更高的结合能,表明表面附近的带越来越强的向下弯曲。这种随时间变化的能带弯曲与表面的污染有关,并且可以通过有意地将表面暴露于一氧化碳和其他物质来加速。对于一个足够强的能带弯曲,额外的状态出现在费米能级。这些被解释为量子化的导带态。对于大的能带弯曲,这些国家被发现进行强Rashba分裂。对于价带态也观察到量子阱态的形成。对类似数据的不同解释也进行了讨论。
Surface adsorption is one of the fundamental processes in numerous fields, including catalysis, environment, energy and medicine. The development of an adsorption model which provides an effective prediction of binding energy in minutes has been a long term goal in surface and interface science. The solution has been elusive as identifying the intrinsic determinants of the adsorption energy for various compositions, structures and environments is non-trivial. We introduce a new and flexible model for predicting adsorption energies to metal substrates. The model is based on easily computed, int…
Thermal and electronic fluctuations of flexible adsorbed molecules: Azobenzene on Ag(111)
我们以Ag(111)表面上的分子开关偶氮苯C $_{12}$ H $_{10}$ N $_{2}$为例,研究了影响柔性吸附物在表面上有限温度吸附性质的热和电子集体涨落.使用第一性原理分子动力学模拟,我们得到的吸附自由能,准确地占熵的贡献,而列入多体分散相互作用占电子相关性,管理吸附结合。我们发现吸附质的性质是强烈的熵驱动,可以判断的动力学分子解吸前因子10 $^{24}$ s $^{-1}$,大大超过以前报道的估计。我们将这种效应与结构和电子观测量的相当大的波动联系起来。我们的计算程序升温脱附测量的比较表明,有限温度效应发挥主导作用的柔性分子与极化表面接触,最近开发的第一性原理方法提供了一个最佳的工具,以揭示新的集体行为在这样的复杂系统。
We investigate the impact of various levels of approximation in density functional theory calculations for the structural and binding properties of the prototypical halide perovskite MAPbI$_3$. Specifically, we test how the inclusion of different correction schemes for including dispersive interactions, and how in addition using hybrid density functional theory, affects the results for pertinent structural observables by means of comparison to experimental data. In particular, the impact of finite temperature on the lattice constants and bulk modulus, and the role of dispersive interactions in…
Using ab initio thermodynamics, the stability of a wide range of hydrocarbon adsorbates under various chemical vapor deposition (CVD) conditions (temperature, methane and hydrogen pressures) used in experimental graphene growth protocols at solid and liquid Cu surfaces has been explored. At the employed high growth temperatures around the melting point of Cu, we find that commonly used thermodynamic models such as the harmonic oscillator model may no longer be accurate. Instead, we account for the translational and rotational mobility of adsorbates using a recently developed hindered translato…
Conventional Oxide dispersion strengthened steels are characterized by thermally stable, high density of Y-Ti-O nanoclusters, which are responsible for their high creep strength. Ti plays a major role in obtaining a high density of ultrafine particles of optimum size range of 2-10 nm. In Al-containing ODS steels developed for corrosion resistance, Y-Al-O clusters formed are of size range 20 -100 nm, and Ti fails in making dispersions finer in the presence of Al. Usage of similar alloying elements like Zr in place of Ti is widely considered. In this study, binding energies of different stages o…
The enormous structural and chemical diversity of metal-organic frameworks (MOFs) forces researchers to actively use simulation techniques on an equal footing with experiments. MOFs are widely known for outstanding adsorption properties, so precise description of host-guest interactions is essential for high-throughput screening aimed at ranking the most promising candidates. However, highly accurate ab initio calculations cannot be routinely applied to model thousands of structures due to the demanding computational costs. On the other side, methods based on force field (FF) parametrization s…
Clear influence of particle size, surfactants and dispersion medium on surface plasmon resonance (SPR) features of Ag nanoparticles (NPs), synthesized in thermal decomposition method, in the broad range of ultraviolet (UV) radiation, critical for many potential applications such as a photocatalyst, UV-sensor and detector, has been demonstrated here. It involves adsorbate coverage, interparticle distance or agglomeration, surface charge density and solvent refractive index (μ). NP agglomeration and surface charge density in solvents of varying μ have been studied systematically through zeta-pot…