20 results on '"Peter Kraus"'
Search Results
2. Quantum Chemistry Common Driver and Databases (QCDB) and Quantum Chemistry Engine (QCEngine): Automation and interoperability among computational chemistry programs
- Author
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Johannes Steinmetzer, Daniel A. Smith, C. David Sherrill, Mark S. Gordon, Nuwan De Silva, Jamshed Anwar, Fang Liu, Henry F. Schaefer, Justin M. Turney, Lee-Ping Wang, Maximilian Scheurer, Annabelle Lolinco, Doaa Altarawy, Jiří Šponer, John D. Chodera, Carlos H. Borca, Rollin A. King, Asem Alenaizan, Jeffrey B. Schriber, David Dotson, Jonathon P. Misiewicz, Heather J. Kulik, Andrew C. Simmonett, Jeffrey R. Wagner, Sebastian J. R. Lee, Theresa L. Windus, Taylor A. Barnes, Peter Kraus, Matthew Welborn, Lori A. Burns, Logan Ward, Andreas Dreuw, Holger Kruse, Devin A. Matthews, Jiyoung Lee, Farhad Ramezanghorbani, Jan Hermann, Roberto Di Remigio, Levi N. Naden, Todd J. Martínez, Joshua T. Horton, John F. Stanton, Sebastian Ehlert, Colton B. Hicks, Adrian G. Hurtado, Zachary L. Glick, Alexander G. Heide, and Michael F. Herbst
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Computer science ,Computation ,Interoperability ,General Physics and Astronomy ,010402 general chemistry ,computer.software_genre ,01 natural sciences ,ARTICLES ,Software ,Engineering ,Composability ,0103 physical sciences ,Physical and Theoretical Chemistry ,Chemical Physics ,010304 chemical physics ,Database ,Application programming interface ,business.industry ,Modular design ,Automation ,0104 chemical sciences ,Networking and Information Technology R&D (NITRD) ,Physical Sciences ,Chemical Sciences ,GAMESS ,business ,computer - Abstract
Community efforts in the computational molecular sciences (CMS) are evolving toward modular, open, and interoperable interfaces that work with existing community codes to provide more functionality and composability than could be achieved with a single program. The Quantum Chemistry Common Driver and Databases (QCDB) project provides such capability through an application programming interface (API) that facilitates interoperability across multiple quantum chemistry software packages. In tandem with the Molecular Sciences Software Institute and their Quantum Chemistry Archive ecosystem, the unique functionalities of several CMS programs are integrated, including CFOUR, GAMESS, NWChem, OpenMM, Psi4, Qcore, TeraChem, and Turbomole, to provide common computational functions, i.e., energy, gradient, and Hessian computations as well as molecular properties such as atomic charges and vibrational frequency analysis. Both standard users and power users benefit from adopting these APIs as they lower the language barrier of input styles and enable a standard layout of variables and data. These designs allow end-to-end interoperable programming of complex computations and provide best practices options by default.
- Published
- 2021
3. Extrapolating DFT Toward the Complete Basis Set Limit: Lessons from the PBE Family of Functionals
- Author
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Peter Kraus
- Subjects
Set (abstract data type) ,Work (thermodynamics) ,Current (mathematics) ,Extrapolation ,Density functional theory ,Statistical physics ,Limit (mathematics) ,Physical and Theoretical Chemistry ,Diatomic molecule ,Basis set ,Computer Science Applications ,Mathematics - Abstract
Extrapolation of density functional theory results from 2- and 3-ζ calculations is a promising method for extracting higher accuracy data from calculations of systems at the affordability limit. In this work, the author presents formulas for the determination of extrapolation parameters, which account for the makeup of the density functional approximation. The formulas are fitted to reproduce the complete basis set limit energies of PBE and related density functional approximations, using a set of 30 singlet diatomics. Their performance is extensively evaluated using standard benchmark data sets. The current systematically derived expressions are shown to be transferrable outside the PBE family of functional approximations, with the resulting extrapolation parameters outperforming the previous, less-systematic values. A good performance of [2,3]-ζ extrapolations for interaction energies of systems with significant noncovalent character is confirmed and holds even in systems of ∼100 atoms in size.
- Published
- 2021
4. Determination of the 'privileged structure' of 8-hydroxyquinoline
- Author
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Dennis Wachsmuth, Peter Kraus, Juan Wang, Jens-Uwe Grabow, Donald McNaughton, and Sven Herbers
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Coupling constant ,Physics ,Spectroscopy of Cold Molecules ,Quadrupole ,Molecule ,Isotopologue ,Rotational spectroscopy ,Rotational–vibrational spectroscopy ,Physical and Theoretical Chemistry ,Atomic physics ,Ground state ,Atomic and Molecular Physics, and Optics ,Equilibrium constant - Abstract
An accurate semi-experimental equilibrium structure of 8-hydroxyquinoline (8-HQ) has been determined combining experiment and theory. The cm-wave rotational spectrum of 8-HQ was recorded in a pulsed supersonic jet using broadband dual-path reflection and narrowband Fabry-Perot-type resonator Fourier-transform microwave spectrometers. Accurate rotational and quartic centrifugal distortion constants and 14 N quadrupole coupling constants are determined. Rotational constants of all 13 C, 18 O and 15 N singly substituted isotopologues in natural abundance and those of a chemically synthesized OD isotopologue were used to obtain geometric parameters for all the heavy atoms and the hydroxyl hydrogen from a number of structure determination models. Theoretical approaches allowed for the determination of a semi-experimental equilibrium structure, reSE in which computed rovibrational and electronic corrections were utilized to convert vibrational ground state constants into equilibrium constants. Despite the molecule having only a horizontal plane of symmetry and possessing 11 individual heavy atoms, microwave spectroscopy has allowed for a reliable and accurate structure determination. A mass dependent, rm2 structure was determined and proved to be equally reliable by comparison with the B3LYP-D3(BJ)/aVTZ equilibrium structure.
- Published
- 2021
- Full Text
- View/download PDF
5. It's a gas: oxidative dehydrogenation of propane over boron nitride catalysts
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Peter Kraus and R.P. Lindstedt
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Technology ,Materials science ,High selectivity ,Inorganic chemistry ,Materials Science ,Materials Science, Multidisciplinary ,02 engineering and technology ,Oxidative phosphorylation ,010402 general chemistry ,01 natural sciences ,Physical Chemistry ,09 Engineering ,Catalysis ,chemistry.chemical_compound ,Propane ,10 Technology ,Dehydrogenation ,Physical and Theoretical Chemistry ,Nanoscience & Nanotechnology ,Science & Technology ,Chemistry, Physical ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Chemistry ,General Energy ,chemistry ,Boron nitride ,Physical Sciences ,Science & Technology - Other Topics ,0210 nano-technology ,03 Chemical Sciences - Abstract
Boron nitride and related boron-containing materials have recently been suggested as very promising catalysts in the oxidative dehydrogenation of propane. The high selectivity toward propylene at comparably high conversion significantly exceeds the performance of established vanadium-based catalysts. In the current work we show that the high selectivity toward propylene and ethylene is fully consistent with a gas-phase conversion mechanism and that it can be modeled reasonably well by the recent detailed microkinetic reaction mechanism of Hashemi and co-workers [ Proc. Combust. Inst. 2019, 37, 461]. Our analysis, using six heterogeneous catalytic reaction pathways, each representing a hypothetical limit case, shows that the boron nitride catalyst is responsible for initiating the gas-phase chemistry. The increased conversion of propane in cases with water cofeed, as well as the trends in the selectivities of minor species upon dilution of the catalytic bed and upon varying the C3H8/O2 inlet ratio, as observed by Venegas and Hermans [ Org. Process Res. Dev. 2018, 22, 1644], are here explained as gas-phase phenomena. Hence, the oxidative dehydrogenation of propane over boron nitride catalysts is an example of a coupled gas and catalytic chemistry system. The current work also highlights the importance of modeling of the complete heated zone, including the rear heat shields and reactor padding if present.
- Published
- 2021
6. Materials genes of heterogeneous catalysis from clean experiments and artificial intelligence
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Lucas Foppa, Maike Hashagen, Spencer J. Carey, Annette Trunschke, Michael Hävecker, Luca M. Ghiringhelli, Pierre Kube, Andrey Tarasov, Matthias Scheffler, Peter Kraus, Frank Girgsdies, Frank Rosowski, and Robert Schlögl
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Flexibility (engineering) ,Condensed Matter - Materials Science ,business.industry ,media_common.quotation_subject ,Materials Science (cond-mat.mtrl-sci) ,FOS: Physical sciences ,Experimental data ,02 engineering and technology ,Condensed Matter Physics ,Heterogeneous catalysis ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Set (abstract data type) ,Identification (information) ,General Materials Science ,Artificial intelligence ,Physical and Theoretical Chemistry ,Symbolic regression ,business ,Function (engineering) ,0210 nano-technology ,Interpretability ,media_common - Abstract
Abstract The performance in heterogeneous catalysis is an example of a complex materials function, governed by an intricate interplay of several processes (e.g., the different surface chemical reactions, and the dynamic restructuring of the catalyst material at reaction conditions). Modeling the full catalytic progression via first-principles statistical mechanics is impractical, if not impossible. Instead, we show here how a tailored artificial-intelligence approach can be applied, even to a small number of materials, to model catalysis and determine the key descriptive parameters (“materials genes”) reflecting the processes that trigger, facilitate, or hinder catalyst performance. We start from a consistent experimental set of “clean data,” containing nine vanadium-based oxidation catalysts. These materials were synthesized, fully characterized, and tested according to standardized protocols. By applying the symbolic-regression SISSO approach, we identify correlations between the few most relevant materials properties and their reactivity. This approach highlights the underlying physicochemical processes, and accelerates catalyst design. Impact statement Artificial intelligence (AI) accepts that there are relationships or correlations that cannot be expressed in terms of a closed mathematical form or an easy-to-do numerical simulation. For the function of materials, for example, catalysis, AI may well capture the behavior better than the theory of the past. However, currently the flexibility of AI comes together with a lack of interpretability, and AI can only predict aspects that were included in the training. The approach proposed and demonstrated in this IMPACT article is interpretable. It combines detailed experimental data (called "clean data") and symbolic regression for the identification of the key descriptive parameters (called "materials genes") that are correlated with the materials function. The approach demonstrated here for the catalytic oxidation of propane will accelerate the discovery of improved or novel materials while also enhancing physical understanding.
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- 2021
7. Basis Set Extrapolations for Density Functional Theory
- Author
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Peter Kraus
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010304 chemical physics ,Basis (linear algebra) ,Extrapolation ,01 natural sciences ,Computer Science Applications ,Quality (physics) ,0103 physical sciences ,Convergence (routing) ,Density functional theory ,Fraction (mathematics) ,Limit (mathematics) ,Statistical physics ,Physical and Theoretical Chemistry ,Wave function ,Basis set ,Mathematics - Abstract
Basis set extrapolation is a common technique in wavefunction theory used to squeeze better performance out of the highest affordable level of theory by combining it with lower quality calculations. In this work, I present analogous techniques for basis set extrapolation in density functional theory, focusing on [2,3]-ζ calculations and including double hybrid and dispersion-corrected functionals. My recommendations are based on basis set limit data from finite element calculations and estimates of basis set limits for double hybrid corrections, and they are validated using the GMTKN55 and NCDT datasets. A short review of extrapolation methods for Hartree-Fock calculations based on modern finite element data is carried out to inform this work. Extrapolation of [2,3]-ζ calculations in def2-Xzvpd and cc-pvXz-pp basis sets with the proposed recipes routinely matches and sometimes outperforms 4-ζ calculations at a fraction of the cost. The methods are implemented in Psi4, allowing for an automated and intuitive application.
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- 2020
8. Psi4 1.4: Open-source software for high-throughput quantum chemistry
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Bernard R. Brooks, Robert A. Shaw, Uğur Bozkaya, Holger Kruse, C. David Sherrill, Francesco A. Evangelista, Konrad Patkowski, Susi Lehtola, A. Eugene DePrince, Zachary L. Glick, Maximilian Scheurer, Lori A. Burns, Matthew C. Schieber, T. Daniel Crawford, Peter Kraus, Justin M. Turney, Rollin A. King, Jonathon P. Misiewicz, Dominic A. Sirianni, Ashutosh Kumar, Yi Xie, Alexander Yu. Sokolov, Jonathan M. Waldrop, Jeffrey B. Schriber, Edward G. Hohenstein, Andrew C. Simmonett, Daniel G. A. Smith, Robert M. Parrish, Joseph Senan O’Brien, Henry F. Schaefer, Raimondas Galvelis, Roberto Di Remigio, Asem Alenaizan, Andrew M. James, Benjamin P. Pritchard, and Department of Chemistry
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Computer science ,Computation ,Interoperability ,116 Chemical sciences ,General Physics and Astronomy ,FRAGMENT POTENTIAL METHOD ,02 engineering and technology ,010402 general chemistry ,computer.software_genre ,01 natural sciences ,DENSITY-FUNCTIONAL THEORY ,ARTICLES ,Software ,CONFIGURATION-INTERACTION ,0103 physical sciences ,Physical and Theoretical Chemistry ,010306 general physics ,Implementation ,computer.programming_language ,010304 chemical physics ,business.industry ,Programming language ,ANALYTIC ENERGY GRADIENTS ,FROZEN NATURAL ORBITALS ,Python (programming language) ,COUPLED-CLUSTER METHODS ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Workflow ,EXCITED-STATES ,SINGLE-REFERENCE ,Component-based software engineering ,Density functional theory ,EXCITATION-ENERGIES ,ADAPTED PERTURBATION-THEORY ,business ,0210 nano-technology ,computer - Abstract
Psi4 is a free and open-source ab initio electronic structure program providing Hartree–Fock, density functional theory, many-body perturbation theory, configuration interaction, density cumulant theory, symmetry-adapted perturbation theory, and coupled-cluster theory. Most of the methods are quite efficient thanks to density fitting and multi-core parallelism. The program is a hybrid of C++ and Python, and calculations may be run with very simple text files or using the Python API, facilitating post-processing and complex workflows; method developers also have access to most of Psi4’s core functionality via Python. Job specification may be passed using The Molecular Sciences Software Institute (MolSSI) QCSchema data format, facilitating interoperability. A rewrite of our top-level computation driver, and concomitant adoption of the MolSSI QCArchive Infrastructure project, make the latest version of Psi4 well suited to distributed computation of large numbers of independent tasks. The project has fostered the development of independent software components that may be reused in other quantum chemistry programs.
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- 2020
9. XeOCS: relatively straightforward?
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Dennis Wachsmuth, Peter Kraus, Daniel A. Obenchain, Jens-Uwe Grabow, Irmgard Frank, and Sven Herbers
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Physics ,Basis (linear algebra) ,Binding energy ,Extrapolation ,General Physics and Astronomy ,Rotational spectroscopy ,Physical and Theoretical Chemistry ,Wave function ,Relativistic quantum chemistry ,Molecular physics - Abstract
We report a benchmark-quality equilibrium-like structure of the Xe⋯OCS complex, obtained from microwave spectroscopy. The experiments are supported by a wide array of highly accurate calculations, expanding the analysis to the complexes of He, Ne, Ar, Kr, Xe, and Hg with OCS. We investigate the trends in the structures and binding energies of the complexes. The assumption that the structure of the monomers does not change significantly upon forming a weakly bound complex is also tested. An attempt at reproducing the r(2)m structure of the Xe⋯OCS complex with correlated wavefunction theory is made, highlighting the importance of relativistic effects, large basis sets, and inclusion of diffuse functions in extrapolation recipes.
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- 2020
10. Benchmark-Quality Semiexperimental Structural Parameters of van der Waals Complexes
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Irmgard Frank, Daniel A. Obenchain, and Peter Kraus
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chemistry.chemical_classification ,Work (thermodynamics) ,010304 chemical physics ,Hydrogen bond ,Reference data (financial markets) ,Ab initio ,Thermodynamics ,010402 general chemistry ,01 natural sciences ,0104 chemical sciences ,symbols.namesake ,chemistry ,0103 physical sciences ,symbols ,Non-covalent interactions ,Molecule ,Physical and Theoretical Chemistry ,van der Waals force ,Complement (set theory) - Abstract
Accurate data sets including noncovalent interactions have become essential for benchmarking computational methods. However, while there is much focus on obtaining an accurate description of relative energies, reliable prediction of accurate equilibrium geometries is also important. To facilitate the benchmarking of computed geometries, the current work includes an accurate data set of semiexperimental equilibrium geometries of noncovalent complexes that can be directly compared to ab initio data. The structures are based on high-accuracy spectroscopic data, combined with vibrational corrections at the double-hybrid density functional level. The current work is designed to complement available data sets of semiexperimental geometries of small rigid molecules and ab initio geometries of complexes. The benchmark-quality data comprises 16 complexes and includes dispersion interactions, hydrogen bonding, CH/π···π interactions, and trimers. In addition to the reference data, accurate counterpoise-corrected geometries have been obtained up to the CCSD level, along with interaction energies. A short overview of the performance of computational methods, including dispersion-corrected B3LYP and B2PLYP functionals, is also included.
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- 2018
11. Validating additive correction schemes against gradient‐based extrapolations
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Irmgard Frank and Peter Kraus
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Physics ,Open source ,Gradient based algorithm ,Extrapolation ,Benchmarking ,Statistical physics ,Physical and Theoretical Chemistry ,Condensed Matter Physics ,Atomic and Molecular Physics, and Optics - Published
- 2019
12. Molecular dynamics simulations of liquid–liquid interfaces in an electric field: The water–1,2-dichloroethane interface
- Author
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Paolo Raiteri, Julian Gale, and Peter Kraus
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010304 chemical physics ,General Physics and Astronomy ,Dielectric ,010402 general chemistry ,Electrostatics ,01 natural sciences ,Ewald summation ,Force field (chemistry) ,0104 chemical sciences ,Molecular dynamics ,Polarizability ,Chemical physics ,Electric field ,0103 physical sciences ,Periodic boundary conditions ,Physical and Theoretical Chemistry - Abstract
The polarized interface between two immiscible liquids plays a central role in many technological processes. In particular, for electroanalytical and ion extraction applications, an external electric field is typically used to selectively induce the transfer of ionic species across the interfaces. Given that it is experimentally challenging to obtain an atomistic insight into the ion transfer process and the structure of liquid-liquid interfaces, atomistic simulations have often been used to fill this knowledge gap. However, due to the long-range nature of the electrostatic interactions and the use of 3D periodic boundary conditions, the use of external electric fields in molecular dynamics simulations requires special care. Here, we show how the simulation setup affects the dielectric response of the materials and demonstrate how by a careful design of the system it is possible to obtain the correct electric field on both sides of a liquid-liquid interface when using standard 3D Ewald summation methods. In order to prove the robustness of our approach, we ran extensive molecular dynamics simulations with a rigid-ion and polarizable force field of the water/1,2-dichloroethane interface in the presence of weak external electric fields.
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- 2020
13. Density Functional Theory for Microwave Spectroscopy of Noncovalent Complexes: A Benchmark Study
- Author
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Irmgard Frank and Peter Kraus
- Subjects
chemistry.chemical_classification ,Work (thermodynamics) ,010304 chemical physics ,Functional approximation ,010402 general chemistry ,01 natural sciences ,Molecular physics ,0104 chemical sciences ,chemistry ,Covalent bond ,0103 physical sciences ,Benchmark (computing) ,Non-covalent interactions ,Density functional theory ,Rotational spectroscopy ,Physical and Theoretical Chemistry ,Dispersion (chemistry) - Abstract
In this work, we compare the results obtained with 89 computational methods for predicting noncovalent bond lengths in weakly bound complexes. Evaluations for the performance in noncovalent interaction energies and covalent bond lengths obtained from five other data sets are included. The overall best performing density functional is the ωB97M-V method, achieving balanced results across all three categories. For noncovalent geometries, the best methods include B97M-V, B3LYP-D3(BJ) and DSD-PBEPBE-D3(BJ). The effects of systematic improvement of the density functional approximation and of dispersion corrections are also discussed.
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- 2018
14. Microkinetic mechanisms for partial oxidation of methane over platinum and rhodium
- Author
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R.P. Lindstedt and Peter Kraus
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Technology ,Hydrogen ,SURFACE ,Inorganic chemistry ,Materials Science ,STAGNATION-FLOW ,chemistry.chemical_element ,Thermodynamics ,Materials Science, Multidisciplinary ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Physical Chemistry ,Methane ,09 Engineering ,Rhodium ,Catalysis ,CATALYTIC PARTIAL OXIDATION ,chemistry.chemical_compound ,COMBUSTION ,CO ADSORPTION ,10 Technology ,Partial oxidation ,Physical and Theoretical Chemistry ,Nanoscience & Nanotechnology ,CHEMICAL-KINETICS ,Science & Technology ,Chemistry, Physical ,EVALUATED KINETIC-DATA ,SYNTHESIS GAS ,RH/AL2O3 CATALYSTS ,HYDROGEN ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Collision theory ,Chemistry ,General Energy ,chemistry ,FLUID-MECHANICS ,Physical Sciences ,Science & Technology - Other Topics ,0210 nano-technology ,Platinum ,03 Chemical Sciences ,Bar (unit) - Abstract
A systematic approach for the development of heterogeneous mechanisms is applied and evaluated for the catalytic partial oxidation of methane over platinum (Pt) and rhodium (Rh). The derived mechanisms are self-consistent and based on a reaction class-based framework comprising variational transition state theory (VTST) and two-dimensional collision theory for the calculation of pre-exponential factors with barrier heights obtained using the unity bond index–quadratic exponential potential (UBI–QEP) method. The surface chemistry is combined with a detailed chemistry for the gas phase, and the accuracy of the approach is evaluated over Pt for a wide range of stoichiometries (0.3 ≤ ϕ ≤ 4.0), pressures (2 ≤ P (bar) ≤ 16), and residence times. It is shown that the derived mechanism can reproduce experimental data with an accuracy comparable to that of the prevalent collision theory approach and without the reliance on experimental data for sticking coefficients. The derived mechanism for Rh shows encouraging agreement for a similar set of conditions, and the robustness of the approach is further evaluated by incorporating partial updates via more accurate DFT-determined barrier heights. Substantial differences are noted for some channels (e.g., where reaction progress is strongly influenced by early transition states) though the impact on the overall agreement with experimental data is moderate for the current systems. Remaining discrepancies are explored using sensitivity analyses to establish key parameters. The study suggests that the overall framework is well-suited for the efficient generation of heterogeneous reaction mechanisms, that it can serve to identify key parameters where high accuracy ab initio methods are required, and that it permits the inclusion of such updates as part of a gradual refinement process.
- Published
- 2017
15. Accurate equilibrium structures of methyl methacrylate and methacrylic acid by microwave spectroscopy and dispersion corrected calculations
- Author
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Sven Herbers, Jens-Uwe Grabow, and Peter Kraus
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Materials science ,010304 chemical physics ,Abundance (chemistry) ,Anharmonicity ,General Physics and Astronomy ,Thermodynamics ,010402 general chemistry ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,Methacrylic acid ,chemistry ,0103 physical sciences ,Microwave spectra ,Density functional theory ,Rotational spectroscopy ,Physical and Theoretical Chemistry ,Methyl methacrylate ,Dispersion (chemistry) - Abstract
The rotational constants of s-trans and s-cis methyl methacrylate and methacrylic acid are determined from microwave spectra. All singly substituted heavy-atom isotopologs of the four species are measured in natural abundance. The experimental rotational constants are combined with anharmonic vibrational corrections using the Coulomb-attenuating method, Becke, three-parameter, Lee-Yang-Parr density functional with Grimme’s D3 dispersion corrections and the Becke-Johnson damping function, yielding precise semi-experimental equilibrium rotational constants. These constants are used to determine semi-experimental equilibrium structures with sub-picometer accuracy, suitable for benchmarking purposes.The rotational constants of s-trans and s-cis methyl methacrylate and methacrylic acid are determined from microwave spectra. All singly substituted heavy-atom isotopologs of the four species are measured in natural abundance. The experimental rotational constants are combined with anharmonic vibrational corrections using the Coulomb-attenuating method, Becke, three-parameter, Lee-Yang-Parr density functional with Grimme’s D3 dispersion corrections and the Becke-Johnson damping function, yielding precise semi-experimental equilibrium rotational constants. These constants are used to determine semi-experimental equilibrium structures with sub-picometer accuracy, suitable for benchmarking purposes.
- Published
- 2019
16. Reaction class-based frameworks for heterogeneous catalytic systems
- Author
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R.P. Lindstedt, Peter Kraus, and Toyota Motor Europe NV/SA
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Reaction mechanism ,Technology ,Engineering, Chemical ,Hydrogen ,Energy & Fuels ,General Chemical Engineering ,Ab initio ,Partial oxidation ,0904 Chemical Engineering ,chemistry.chemical_element ,Thermodynamics ,PLATINUM SURFACES ,Combustion ,Catalytic combustion ,0902 Automotive Engineering ,Catalysis ,Adsorption ,Engineering ,METHANE ,HETERO-/HOMOGENEOUS COMBUSTION ,Computational chemistry ,CHEMISTRY ,Fuel reformation ,Physical and Theoretical Chemistry ,SYNGAS ,AB-INITIO ,Science & Technology ,Mechanical Engineering ,PRESSURES ,Surface chemistry ,Collision theory ,Engineering, Mechanical ,chemistry ,Physical Sciences ,HYDROGEN/AIR MIXTURES ,Syngas ,ETHANE ,0913 Mechanical Engineering - Abstract
A systematic and self-consistent approach is applied to study the combustion of hydrogen and syngas over platinum using coupled detailed gas phase and surface reaction mechanisms. The surface chemistry is derived using a reaction class-based framework comprising variational transition state theory (VTST), two-dimensional collision theory and the unity bond index-quadratic exponential potential for barrier heights. The latter approach is augmented by the inclusion of more accurate data, such as the heat of adsorption of CO, and VTST is used to systematically remove the need for the surface sticking coefficients associated with adsorption and desorption processes. Transition-state theory estimates for several reaction classes are produced by combining the M06 family of density functionals with the Stuttgart/Dresden effective core potential for metal atoms. The developed method reproduces experimental data with an accuracy comparable or better than the previously used collision theory approach and without the reliance on experimental parameters. The presented framework is well-suited for the efficient generation of novel heterogeneous reaction mechanisms and also serves to identify key parameters where high accuracy ab initio methods may be required. The latter is exemplified via the sensitivity of selected results to the adsorption of carbon monoxide on platinum.
- Published
- 2016
17. The tardy dance of molecular orbitals
- Author
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Irmgard Frank and Peter Kraus
- Subjects
Physics ,Dance ,010405 organic chemistry ,010402 general chemistry ,Condensed Matter Physics ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,Molecular dynamics ,Atomic orbital ,Quantum mechanics ,Density functional theory ,Molecular orbital ,Physical and Theoretical Chemistry - Published
- 2018
18. Blurring out hydrogen: The dynamical structure of teflic acid
- Author
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Jens-Uwe Grabow, Daniel A. Obenchain, Peter Kraus, Dennis Wachsmuth, and Sven Herbers
- Subjects
Materials science ,Ab initio ,General Physics and Astronomy ,Zero-point energy ,Hydrogen atom ,010402 general chemistry ,01 natural sciences ,Molecular physics ,0104 chemical sciences ,Bond length ,symbols.namesake ,Fourier transform ,0103 physical sciences ,Physics::Atomic and Molecular Clusters ,symbols ,Rotational spectroscopy ,Physical and Theoretical Chemistry ,010306 general physics ,Ground state ,Relativistic quantum chemistry - Abstract
The microwave spectra of 10 teflic acid isotopologues were recorded in the frequency range of 3-25 GHz using supersonic jet-expansion Fourier transform microwave spectroscopy. Despite being asymmetric in its equilibrium structure, the delocalization of the hydrogen atom leads to a symmetric top vibrational ground state structure. In this work, we present the zero point structure obtained from the experimental rotational constants and an approach to determine the semi-experimental equilibrium structure aided by ab initio data. The Te–O bond length determined in the equilibrium structure is accurate to the picometer and can be used as a benchmark for computational methods treating relativistic effects.
- Published
- 2018
19. On the dynamics of H2adsorption on the Pt(111) surface
- Author
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Irmgard Frank and Peter Kraus
- Subjects
Sticking coefficient ,Hydrogen ,Chemistry ,Thermodynamics ,chemistry.chemical_element ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Potential energy ,Atomic and Molecular Physics, and Optics ,Dissociation (chemistry) ,0104 chemical sciences ,Molecular dynamics ,Adsorption ,Physics::Atomic and Molecular Clusters ,Physical chemistry ,Density functional theory ,Physics::Chemical Physics ,Physical and Theoretical Chemistry ,0210 nano-technology ,Molecular beam - Abstract
The dynamics and kinetics of the dissociation of hydrogen over the hexagonal close packed platinum (Pt(111)) surface are investigated using Car–Parrinello molecular dynamics and static density functional theory calculations of the potential energy surfaces. The calculations model the reference energy-resolved molecular beam experiments, considering the degrees of freedom of the catalytic surface. Two-dimensional potential energy surfaces above the main sites on Pt(111) are determined. Combined with Car–Parrinello trajectories, they confirm the dissociative adsorption of H2 as the only adsorption pathway on this surface at H2 incindence energies above 5 kJ/mol. A direct determination of energy-resolved sticking coefficients from molecular dynamics is also performed, showing an excellent agreement with the experimental data at incidence energies in the 5–30 kJ/mol range. Application of dispersion corrections does not lead to an improvement in the prediction of the H2 sticking coefficient. The adsorption reaction rate obtained from the calculated sticking coefficients is consistent with experimentally derived literature values.
- Published
- 2017
20. Systems' optimization: achieving the balance
- Author
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Peter Kraus
- Subjects
Engineering ,Waste management ,Renewable Energy, Sustainability and the Environment ,business.industry ,Energy Engineering and Power Technology ,ComputerApplications_COMPUTERSINOTHERSYSTEMS ,Commercialization ,Anode ,Cogeneration ,Electricity generation ,Natural gas ,Steam turbine ,Systems design ,Capital cost ,Electrical and Electronic Engineering ,Physical and Theoretical Chemistry ,Process engineering ,business - Abstract
Fuel cells for stationary power generation applications are being pursued on a large scale worldwide in an effort to achieve commercialization before the turn of the century. Some aspects of system optimization are discussed illustrating the influence of basic system design possibilities. Design variants investigated include alternatives for anode and cathode gas supply and gas recycling, methods to achieve self-sufficiency on water for the reforming of natural gas, and recovery of unspent fuel from the anode exhaust. Especially in small systems for decentralized applications, e.g., industrial cogeneration, system simplification is decisive to bring down the capital cost of the balance-of-plant. Trade-offs between system complexity and efficiency are possible to optimize the economy. In large plants, high-temperature fuel cell can be supplemented with bottoming cycles for best fuel utilization. Gas turbines and steam turbines can be evaluated, having strong influence on the system design pressures and, therefore, system cost.
- Published
- 1994
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