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  • Smeets, Egidius W.F. and Füchsel, Gernot and Kroes, Geert-Jan: Quantum Dynamics of Dissociative Chemisorption of H2 on the Stepped Cu(211) Surface, The Journal of Physical Chemistry C (2019) DOI: 10.1021/acs.jpcc.9b06539

Reaction on stepped surfaces are relevant to heterogeneous catalysis, in which reaction often takes place at the edges of nanoparticles where the edges resemble steps on single crystal stepped surfaces. Previous results on H2 + Cu(211) show that in this system steps do not enhance the reactivity, and raised the question of whether this effect could be in anyway related to the neglect of quantum dynamical effects in the theory. To investigate this we present full quantum dynamical molecular beam simulations of sticking of H2 on Cu(211) in which all important rovibrational states populated in a molecular beam experiment are taken into account. We find that the reaction of H2 with Cu(211) is very well described with quasi-classical dynamics when simulating molecular beam sticking experiments, in which averaging takes place over a large number of rovibrational states and over translational energy distributions. Our results show that the stepped Cu(211) surface is distinct from its component Cu(111) terraces and Cu(100) steps and cannot be described as a combination of its component parts with respect to the reaction dynamics when considering the orientational dependence. Specifically, we present evidence that at translational energies close to the reaction threshold vibrationally excited molecules show a negative rotational quadrupole alignment parameter on Cu(211), which is not found on Cu(111) and Cu(100). The effect arises because these molecules react with a site specific reaction mechanism at the step, i.e., inelastic rotational enhancement, which is only effective for molecules with a small absolute value of the magnetic rotation quantum number. From a comparison to recent associative desorption experiments as well as Born-Oppenheimer molecular dynamics (BOMD) calculations it follows that the effects of surface atom motion and electron hole-pair (ehp) excitation on the reactivity fall within chemical accuracy, i.e., modeling these effect shifts extracted reaction probability curves by less then 1 kcal/mol translational energy. We found no evidence in our fully-state-resolved calculations for the ’slow’ reaction channel that was recently reported for associative desorption of H2 from Cu(111) and Cu(211), but our results for the fast channel are in good agreement with the experiments of H2 + Cu(211).

  • Stemmle, Christian and Paulus, Beate: Quantification of electron correlation effects: Quantum Information Theory vs Method of Increments, International Journal of Quantum Chemistry 119, e26007 (2019) DOI: 10.1002/qua.26007

Abstract Understanding electron correlation is crucial for developing new concepts in electronic structure theory, especially for strongly correlated electrons. We compare and apply two different approaches to quantify correlation contributions of orbitals: Quantum Information Theory (QIT) based on a Density Matrix Renormalization Group (DMRG) calculation and the Method of Increments (MoI). Although both approaches define very different correlation measures, we show that they exhibit very similar patterns when being applied to a polyacetelene model system. These results suggest one may deduce from one to the other, allowing the MoI to leverage from QIT results by screening correlation contributions with a cheap (“sloppy”) DMRG with a reduced number of block states. Or the other way around, one may select the active space in DMRG from cheap one-body MoI calculations.

  • Rietsch, Philipp and Witte, Felix and Sobottka, Sebastian and Germer, Gregor and Becker, Alexander and Güttler, Arne and Sarkar, Biprajit and Paulus, Beate and Resch-Genger, Ute and Eigler, Siegfried: Diaminodicyanoquinones: Fluorescent Dyes with High Dipole Moments and Electron-Acceptor Properties, Angewandte Chemie International Edition 58, 8235-8239 (2019) DOI: 10.1002/anie.201903204

Fluorescent dyes are applied in various fields of research, including solar cells and light-emitting devices, and as reporters for assays and bioimaging studies. Fluorescent dyes with an added high dipole moment pave the way to nonlinear optics and polarity sensitivity. Redox activity makes it possible to switch the molecule's photophysical properties. Diaminodicyanoquinone derivatives possess high dipole moments, yet only low fluorescence quantum yields, and have therefore been neglected as fluorescent dyes. Here we investigate the fluorescence properties of diaminodicyanoquinones using a combined theoretical and experimental approach and derive molecules with a fluorescence quantum yield exceeding 90 %. The diaminodicyanoquinone core moiety provides chemical versatility and can be integrated into novel molecular architectures with unique photophysical features.

  • Jia, Fei and Hupatz, Henrik and Yang, Liu-Pan and Schröder, Hendrik V. and Li, Dong-Hao and Xin, Shan and Lentz, Dieter and Witte, Felix and Xie, Xiaojiang and Paulus, Beate and Schalley, Christoph A. and Jiang, Wei: Naphthocage: A Flexible yet Extremely Strong Binder for Singly Charged Organic Cations, Journal of the American Chemical Society 141, 4468-4473 (2019) DOI: 10.1021/jacs.9b00445

We report a quite flexible naphthol-based cage (so-called “naphthocage”) which adopts a self-inclusion conformation in its free state and is able to bind singly charged organic cations extremely strongly (Ka > 107 M–1). Ion-selective electrodes prepared with this naphthocage show a super-Nernstian response to acetylcholine. In addition, the highly stable complex (1010 M–1) between ferrocenium and the naphthocage can be switched electrochemically, which lays a basis for its application in stimuli-responsive materials.

  • Guday, Guy and Donskyi, Ievgen S. and Gholami, Mohammad Fardin and Algara-Siller, Gerardo and Witte, Felix and Lippitz, Andreas and Unger, Wolfgang E. S. and Paulus, Beate and Rabe, Jürgen P. and Adeli, Mohsen and Haag, Rainer: Scalable Production of Nanographene and Doping via Nondestructive Covalent Functionalization, Small 15, 1805430 (2019) DOI: 10.1002/smll.201805430

Abstract A new method for top-down, one-pot, gram-scale production of high quality nanographene by incubating graphite in a dilute sodium hypochlorite solution at only 40 °C is reported here. The produced sheets have only 4 at% oxygen content, comparable with nanographene grown by chemical vapor deposition. The nanographene sheets are covalently functionalized using a nondestructive nitrene [2+1] cycloaddition reaction that preserves their π-conjugated system. Statistical analyses of Raman spectroscopy and X-ray photoelectron spectroscopy indicate a low number of sp3 carbon atoms on the order of 2% before and 4% after covalent functionalization. The nanographene sheets are significantly more conductive than conventionally prepared nanographene oxide, and conductivity further increases after covalent functionalization. The observed doping effects and theoretical studies suggest sp2 hybridization for the carbon atoms involved in the [2+1] cycloaddition reaction leading to preservation of the π-conjugated system and enhancing conductivity via n-type doping through the bridging N-atom. These methods are easily scalable, which opens the door to a mild and efficient process to produce high quality nanographenes and covalently functionalize them while retaining or improving their physicochemical properties.

  • Mattsson, Stefan and Paulus, Beate and Redeker, Frenio A. and Beckers, Helmut and Riedel, Sebastian and Müller, Carsten: The Crystal Structure of α-F2: Solving a 50 Year Old Puzzle Computationally, Chemistry – A European Journal 25, 3318-3324 (2019) DOI: 10.1002/chem.201805300

Abstract The cohesive energy of α-fluorine, with C2/c space group symmetry, was calculated at benchmark quality by applying the method of increments. The known experimental X-ray structure data needed to be refined, since the reported intramolecular bond length was unrealistically large. At the CCSD(T) level, including corrections for zero-point energy, the basis set superposition error, and extrapolated to the complete basis set limit, a cohesive energy of −8.72 kJ mol−1 was calculated, which agrees well with the 0 K-extrapolated experimental value of −8.35 kJ mol−1. Comparison of the C2/c structure with a Cmca structure, isotypic to that of chlorine, bromine, and iodine reveals that the origin of the different structure of solid fluorine, compared to the heavier halogens, is the lack of significantly stabilizing σ-hole interactions. In addition, the wave numbers of the stretching mode in solid fluorine were calculated at coupled cluster level and compared to newly recorded Raman spectra of condensed fluorine. Both experiment and calculation indicate a slight up-shift for the stretching mode by 2 or 5 cm−1, respectively, with respect to a free F2 molecule in the gas phase.

  • ChunMei Liu and Joern Manz and Jean Christophe Tremblay: From Symmetry Breaking via Charge Migration to Symmetry Restoration in Electronic Ground and Excited States: Quantum Control on the Attosecond Time Scale, Applied Sciences 9, 953 (2019) DOI: 10.3390/app9050953

This article starts with an introductory survey of previous work on breaking and restoring the electronic structure symmetry of atoms and molecules by means of two laser pulses. Accordingly, the first pulse breaks the symmetry of the system in its ground state with irreducible representation IRREPg by exciting it to a superposition of the ground state and an excited state with different IRREPe . The superposition state is non-stationary, representing charge migration with period T in the sub- to few femtosecond time domains. The second pulse stops charge migration and restores symmetry by de-exciting the superposition state back to the ground state. Here, we present a new strategy for symmetry restoration: The second laser pulse excites the superposition state to the excited state, which has the same symmetry as the ground state, but different IRREPe . The success depends on perfect time delay between the laser pulses, with precision of few attoseconds. The new strategy is demonstrated by quantum dynamics simulation for an oriented model system, benzene.

  • T. Serwatka and B. Paulus and J. C. Tremblay: A new six-dimensional potential energy surface for NO/Au(111), Molecular Physics 117, 42-57 (2019) DOI: 10.1080/00268976.2018.1492041

In this contribution, we reinvestigate the interaction of nitric oxide with a gold(111) surface using plane-wave density functional theory, with particular emphasis on the role of intermode coupling. A new global representation of the potential energy surface is obtained from the ab initio data by non-linear adjustment, yielding a set of physically motivated parameters. The novel functional form improves on its parent [Marquardt et al. J. Chem. Phys. 132, 074108 (2010)] by addressing the variation of the charge transfer character of the electronic structure data, and by treating surface corrugation via translationally invariant weighting functions of lower-dimensional, high-symmetry sites. Contrary to previous studies, the adsorption minimum does not favour the hollow sites and is found at a strongly tilted orientation (circa 60) on top of a gold atom of the topmost layer. High-dimensional anharmonic vibrational analysis performed using a Lanczos-based contracted iterative procedure reveals that the low-lying excited vibrational states retain a strongly tilted orientation and remain predominantly localised at the atop site. These findings are expected to have important implications for the interpretation of recent NO scattering experiments.

  • Mattsson, Stefan and Paulus, Beate: Density Functional Theory Calculations of Structural, Electronic, and Magnetic Properties of the 3d Metal Trifluorides MF3 (M = Ti-Ni) in the Solid State, Journal of Computational Chemistry 40, 1190-1197 (2019) DOI: 10.1002/jcc.25777

We employ density functional theory with Hubbard U correction or hybrid functionals to study the series of magnetic 3d metal trifluorides MF3 (M = Ti-Ni). Experimental lattice parameters are reproduced with an error margin of 0.5%–4.3%. Cooperative Jahn–Teller distortions are reproduced for MnF3, but also found in TiF3 and CoF3 at smaller levels compared to MnF3. Trends in electronic structure with respect to positions of the d bands are linked to the magnetic properties where M = Ti-Cr are weak magnetic Mott–Hubbard insulators, M = Fe-Ni are strong magnetic charge-transfer insulators and MnF3 falls in between. Our work contributes to the characterization of the relatively unknown NiF3, since FeF3 and CoF3 have similar electronic and magnetic properties. However, NiF3 does not show a Jahn–Teller distortion as present in CoF3.

  • Voloshina, Elena and Guo, Qilin and Paulus, Beate and Böttcher, Stefan and Vita, Hendrik and Horn, Karsten and Zhao, Changbao and Cui, Yi and Dedkov, Yuriy: Electronic Structure and Magnetic Properties of Graphene/Ni3Mn/Ni(111) Trilayer, The Journal of Physical Chemistry C 123, 4994-5002 (2019) DOI: 10.1021/acs.jpcc.9b00942

Experimental and theoretical studies of manganese deposition on graphene/Ni(111) show that a thin ferromagnetic Ni3Mn layer, which is protected by a graphene overlayer, is formed upon Mn intercalation. The electronic bands of graphene are affected by Ni3Mn interlayer formation through a slight reduction of n-type doping compared to graphene/Ni(111) and a suppression of the interface states characteristic of graphene/Ni(111). Our density functional theory-based theoretical analysis of interface geometric, electronic, and magnetic structure gives strong support to our interpretation of the experimental scanning tunneling microscopy, low energy electron diffraction, and photoemission results and shows that the magnetic properties of graphene on Ni(111) are strongly influenced by Ni3Mn formation.

  • Füchsel, Gernot and Zhou, Xueyao and Jiang, Bin and Juaristi, J. Inaki and Alducin, Maite and Guo, Hua and Kroes, Geert-Jan: Reactive and Nonreactive Scattering of HCl from Au(111): An Ab Initio Molecular Dynamics Study, The Journal of Physical Chemistry C 123, 2287-2299 (2019) DOI: 10.1021/acs.jpcc.8b10686

The HCl + Au(111) system has recently become a benchmark for highly activated dissociative chemisorption, which presumably is strongly affected by electron–hole pair excitation. Previous dynamics calculations, which were based on density functional theory at the generalized gradient approximation level (GGA-DFT) for the molecule–surface interaction, have all overestimated measured reaction probabilities by at least an order of magnitude. Here, we perform ab initio molecular dynamics (AIMD) and AIMD with electronic friction (AIMDEF) calculations employing a density functional that includes the attractive van der Waals interaction. Our calculations model the simultaneous and possibly synergistic effects of surface temperature, surface atom motion, electron–hole pair excitation, the molecular beam conditions of the experiments, and the van der Waals interaction on the reactivity. We find that reaction probabilities computed with AIMDEF and the SRP32-vdW functional still overestimate the measured reaction probabilities, by a factor 18 for the highest incidence energy at which measurements were performed (≈2.5 eV). Even granting that the experiment could have underestimated the sticking probability by about a factor three, this still translates into a considerable overestimation of the reactivity by the current theory. Likewise, scaled transition probabilities for vibrational excitation from ν = 1, j = 1 to ν = 2 are overestimated by the AIMDEF theory, by factors 3–8 depending on the initial conditions modeled. Energy losses to the surface and translational energy losses are, however, in good agreement with experimental values.

  • Ghassemi, Elham Nour and Smeets, Egidius W. F. and Somers, Mark F. and Kroes, Geert-Jan and Groot, Irene M. N. and Juurlink, Ludo B. F. and Füchsel, Gernot: Transferability of the Specific Reaction Parameter Density Functional for H2 + Pt(111) to H2 + Pt(211), The Journal of Physical Chemistry C 123, 2973-2986 (2019) DOI: 10.1021/acs.jpcc.8b11018

The accurate description of heterogeneously catalyzed reactions may require chemically accurate evaluation of barriers for reactions of molecules at the edges of metal nanoparticles. It was recently shown that a semiempirical density functional describing the interaction of a molecule dissociating on a flat metal surface (CHD3 + Pt(111)) is transferable to the same molecule reacting on a stepped surface of the same metal (Pt(211)). However, validation of the method for additional systems is desirable. To address the question whether the specific reaction parameter (SRP) functional that describes H2 + Pt(111) with chemical accuracy is also capable of accurately describing H2 + Pt(211), we have performed molecular beam simulations with the quasi-classical trajectory (QCT) method, using the SRP functional developed for H2 + Pt(111). Our calculations used the Born–Oppenheimer static surface model. The accuracy of the QCT method was assessed by comparison with quantum dynamics results for reaction of the ro-vibrational ground state of H2. The theoretical results for sticking of H2 and D2 on Pt(211) are in quite good agreement with the experiment, but uncertainties remain because of a lack of accuracy of the QCT simulations at low incidence energies and possible inaccuracies in the reported experimental incidence energies at high energies. We also investigated the nonadiabatic effect of electron–hole pair excitation on the reactivity using the molecular dynamics with the electron friction (MDEF) method, employing the local density friction approximation (LDFA). Only small effects of electron–hole pair excitation on sticking are found.

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This page was last modified on October 10, 2019, at 02:13 PM