Shared posts
[ASAP] Surface-Plasmon-Induced Ammonia Decomposition on Copper: Excited-State Reaction Pathways Revealed by Embedded Correlated Wavefunction Theory
[ASAP] Electronic Properties of Realistic Anatase TiO2 Nanoparticles from G0W0 Calculations on a Gaussian and Plane Waves Scheme
WavePacket: A Matlab package for numerical quantum dynamics. III. Quantum‐classical simulations and surface hopping trajectories
Population dynamics for a generalized three‐state Jahn‐Teller system: Quantum‐mechanical (full curves) versus quantum‐classical propagations by means of fewest switches surface hopping (dashed curves) and single switch surface hopping (dash‐dotted curves).
WavePacket is an open‐source program package for numerical simulations in quantum dynamics. Building on the previous Part I (Schmidt and Lorenz, Comput. Phys. Commun. 2017, 213, 223] and Part II (Schmidt and Hartmann, Comput. Phys. Commun. 2018, 228, 229] which dealt with quantum dynamics of closed and open systems, respectively, the present Part III adds fully classical and mixed quantum‐classical propagation techniques to WavePacket. There classical phase‐space densities are sampled by trajectories which follow (diabatic or adiabatic) potential energy surfaces. In the vicinity of (genuine or avoided) intersections of those surfaces, trajectories may switch between them. To model these transitions, two classes of stochastic algorithms have been implemented: (1) Tully's fewest switches surface hopping and (2) Landau–Zener‐based single switch surface hopping. The latter one offers the advantage of being based on adiabatic energy gaps only, thus not requiring nonadiabatic coupling information any more. The present work describes the MATLAB version of WavePacket 6.1.0, which is essentially an object‐oriented rewrite of previous versions, allowing to perform fully classical, quantum‐classical and quantum‐mechanical simulations on an equal footing, that is, for the same physical system described by the same WavePacket input. The software package is hosted and further developed at the Sourceforge platform, where also extensive Wiki‐documentation as well as numerous worked‐out demonstration examples with animated graphics are available. © 2019 Wiley Periodicals, Inc.
Two-layer Gaussian-based MCTDH study of the S1 ← S0 vibronic absorption spectrum of formaldehyde using multiplicative neural network potentials
The absorption spectrum of the vibronically allowed S1(1A2) ← S0(1A1) transition of formaldehyde is computed by combining multiplicative neural network (NN) potential surface fits, based on multireference electronic structure data, with the two-layer Gaussian-based multiconfiguration time-dependent Hartree (2L-GMCTDH) method. The NN potential surface fit avoids the local harmonic approximation for the evaluation of the potential energy matrix elements. Importantly, the NN surface can be constructed so as to be physically well-behaved outside the domain spanned by the ab initio data points. A comparison with experimental results shows spectroscopic accuracy of the converged surface and 2L-GMCTDH quantum dynamics.
[ASAP] Using Artificial Intelligence To Forecast Water Oxidation Catalysts
[ASAP] Argon Embedded by Ion Bombardment: Relevance of Hidden Dopants in Rutile TiO2
[ASAP] Opportunities and Knowledge Gaps of SO2 Electrocatalytic Oxidation for H2 Electrochemical Generation
[ASAP] Oxidation-State Constrained Density Functional Theory for the Study of Electron-Transfer Reactions
[ASAP] Scaling Relation of Oxygen Reduction Reaction Intermediates at Defective TiO2 Surfaces
Methanol oxidation on the Pt(321) surface: a theoretical approach on the role of surface morphology and surface coverage effects
DOI: 10.1039/C9CP03291F, Paper
We investigated methanol oxidation, decomposition and carbonylation reactions on a high indexed Pt(321) surface.
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[ASAP] Effect of the Solvent on the Oxygen Evolution Reaction at the TiO2–Water Interface
[ASAP] Photoinduced Water–Heptazine Electron-Driven Proton Transfer: Perspective for Water Splitting with g-C3N4
[ASAP] PES-Learn: An Open-Source Software Package for the Automated Generation of Machine Learning Models of Molecular Potential Energy Surfaces
Machine learning for potential energy surfaces: An extensive database and assessment of methods
On the basis of a new extensive database constructed for the purpose, we assess various Machine Learning (ML) algorithms to predict energies in the framework of potential energy surface (PES) construction and discuss black box character, robustness, and efficiency. The database for training ML algorithms in energy predictions based on the molecular structure contains SCF, RI-MP2, RI-MP2-F12, and CCSD(F12*)(T) data for around 10.5 × 106 configurations of 15 small molecules. The electronic energies as function of molecular structure are computed from both static and iteratively refined grids in the context of automized PES construction for anharmonic vibrational computations within the n-mode expansion. We explore the performance of a range of algorithms including Gaussian Process Regression (GPR), Kernel Ridge Regression, Support Vector Regression, and Neural Networks (NNs). We also explore methods related to GPR such as sparse Gaussian Process Regression, Gaussian process Markov Chains, and Sparse Gaussian Process Markov Chains. For NNs, we report some explorations of architecture, activation functions, and numerical settings. Different delta-learning strategies are considered, and the use of delta learning targeting CCSD(F12*)(T) predictions using, for example, RI-MP2 combined with machine learned CCSD(F12*)(T)-RI-MP2 differences is found to be an attractive option.
BSSE‐correction scheme for consistent gaussian basis sets of double‐ and triple‐zeta valence with polarization quality for solid‐state calculations
Revised versions of our pob‐TZVP and pob‐DZVP basis sets have been derived for the elements HBr for periodic quantum‐chemical solid state calculations, denoted as pob‐TZVP‐rev2 and pob‐DZVP‐rev2. To reduce the basis set superposition error, the authors took into account the counterpoise energy of hydride dimers as an additional parameter in the basis set optimization. The overall performance of the rev2 basis sets is significantly improved compared to the original pob basis sets.
Revised versions of our published pob‐TZVP [Peintinger, M. F.; Oliveira, D. V. and Bredow, T., J. Comput. Chem., 2013, 34 (6), 451–459.] and unpublished pob‐DZVP basis sets, denoted as pob‐TZVP‐rev2 and pob‐DZVP‐rev2, have been derived for the elements HBr. It was observed that the pob basis sets suffer from the basis set superposition error (BSSE). In order to reduce this effect, we took into account the counterpoise energy of hydride dimers as an additional parameter in the basis set optimization. The overall performance, portability, and SCF stability of the resulting rev2 basis sets are significantly improved compared to the original pob basis sets. © 2019 Wiley Periodicals, Inc.
Binding of multiple SO2 molecules to small gold cluster anions (AuN−, AuNOH−, N = 1‐8)
Density functional theory and flow‐reactor experiments are used to study the adsorption of SO2 on gas‐phase small gold cluster anions and their hydroxide derivatives. All clusters adsorb up to four SO2 molecules, and the gold‐hydroxide clusters are more active for SO2 adsorption.
Abstract
The binding of SO2 on gas‐phase gold cluster anions, AuN −, and their hydroxide counterparts, AuNOH−, have been studied using density functional theory combined with flow reactor/time‐of‐flight mass spectrometry techniques. SO2 is adsorbed on all of the AuN − and AuNOH− clusters (N = 1‐8) and the hydroxide clusters are more active than the bare anionic clusters. Successive additions of SO2 molecules (up to four) have been analyzed. In all cases, anionic clusters are shown to bind multiple SO2 molecules. Theoretical analyses are in agreement with the experimental results, showing that the addition of more than one molecule is thermodynamically favorable. Larger clusters do not necessarily absorb more molecules, as different SO2 binding motifs on these clusters are present. These results provide important insight for the potential use of these anionic clusters as SO2 hunters.
[ASAP] Benchmarks for Electronically Excited States with CASSCF Methods
[ASAP] Interface Modulation of Two-Dimensional Superlattices for Efficient Overall Water Splitting
autoCAS: A Program for Fully Automated Multiconfigurational Calculations
autoCAS program for fully automated multiconfigurational calculations is presented. The program requires a minimal input, comparable to that of a density‐functional theory calculation and automatically selects an appropriate active space based on orbital entanglement entropies calculated from a partially converged density‐matrix renormalization group calculation. Hence, autoCAS turns multiconfigurational calculations into a black‐box method. It is implemented as a graphical user interface and is part of the SCINE project for chemical interaction networks.
We present our implementation autoCAS for fully automated multiconfigurational calculations, which we also make available free of charge on our webpages. The graphical user interface of autoCAS connects a general electronic structure program with a density‐matrix renormalization group program to carry out our recently introduced automated active space selection protocol for multiconfigurational calculations (Stein and Reiher, J. Chem. Theory Comput., 2016, 12, 1760). Next to this active space selection, autoCAS carries out several steps of multiconfigurational calculations so that only a minimal input is required to start them, comparable to that of a standard Kohn–Sham density‐functional theory calculation, so that black‐box multiconfigurational calculations become feasible. Furthermore, we introduce a new extension to the selection algorithm that facilitates automated selections for molecules with large valence orbital spaces consisting of several hundred orbitals. © 2019 Wiley Periodicals, Inc.
Photocatalytic activity of TiO2 nanoparticles: a theoretical aspect
DOI: 10.1039/C9TA03385H, Review Article
Recent theoretical studies on geometric and chemical modification strategies, band engineering, and charge carrier dynamics of TiO2 nanoparticles are discussed.
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[ASAP] Strong Influence of Oxygen Vacancy Location on Charge Carrier Losses in Reduced TiO2 Nanoparticles
CRYSPLOT: A new tool to visualize physical and chemical properties of molecules, polymers, surfaces, and crystalline solids
CRYSPLOT is a publicly accessible web‐based tool (http://crysplot.crystalsolutions.eu) to visualize physico‐chemical properties of periodic systems (i.e., crystals, surfaces and polymers) as computed with the CRYSTAL code. It has been designed as a very intuitive graphical tool, a low entry‐level interface, to all types of users, from beginners to experts, and purposes, from education to research, as shown with selected examples.
CRYSPLOT is a web‐oriented tool (http://crysplot.crystalsolutions.eu) to visualize computed properties of periodic systems, in particular, as computed with the CRYSTAL code. Along with plotting, CRYSPLOT also permits the modification and customization of plots to meet the standards required for scientific graphics. CRYSPLOT has been designed with advanced and freely available graphical Javascript libraries as Plotly. The programming language used is Javascript. The code parses the input files, reads the data, and organizes them into objects ready to be plotted with the plotly.js library. It is modular and flexible so that it is very simple to add other input data formats. The new graphical tool is presented in details along with selected applications on metal–organic frameworks to show some of its capabilities. © 2019 Wiley Periodicals, Inc.
Effect of oxygen deficiency on the excited state kinetics of WO3 and implications for photocatalysis
DOI: 10.1039/C9SC00693A, Edge Article
Using WO3 as a model material, we investigate how different oxygen vacancy concentrations affect trapping of photogenerated charges and photocatalytic reactions in metal oxides.
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[ASAP] Excited-State Potential Energy Surfaces, Conical Intersections, and Analytical Gradients from Ground-State Density Functional Theory
[ASAP] Role of Heterojunction in Charge Carrier Separation in Coexposed Anatase (001)–(101) Surfaces
[ASAP] Selectivity of Photoelectrochemical Water Splitting on TiO2 Anatase Single Crystals
Triplet state promoted reaction of SO2 with H2O by competition between proton coupled electron transfer (pcet) and hydrogen atom transfer (hat) processes
DOI: 10.1039/C9CP01105F, Paper
The excited triplet electronic state of SO2 (a3B1) reacts with water through a proton coupled electron transfer (pcet) mechanism rather than via a conventional hydrogen atom transfer (hat) process.
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Accurate characterization of the lowest triplet potential energy surface of SO2 with a coupled cluster method
The near-equilibrium potential energy surface (PES) of the [math] state of SO2 is developed from explicitly correlated spin-unrestricted coupled cluster calculations with single, double, and perturbative triple excitations with an augmented triple-zeta correlation-consistent basis set. The lowest-lying ro-vibrational energy levels of several sulfur isotopologues have been determined using this PES. It is shown that the new ab initio PES provides a much better description of the low-lying vibrational states than a previous PES determined at the multi-reference configuration interaction level. In particular, the theory-experiment agreement for the three lowest-lying vibrational transitions is within 1–3 cm−1.
Mathematik: Die schnellste Art zu multiplizieren
A perturbation‐based super‐CI approach for the orbital optimization of a CASSCF wave function
A perturbation theory‐based algorithm for the iterative orbital update in complete active space self‐consistent‐field (CASSCF) calculations is presented. It is based on single‐excitation amplitudes obtained from a perturbative configuration interaction calculation using the Dyall Hamiltonian as a zeroth‐order Hamiltonian. These amplitudes are used for the construction of the exponential of an anti‐Hermitian matrix which can be used for the orbital update. Combined with DIIS, this approach leads to rapid convergence of the CASSCF iteration procedure.
A perturbation theory‐based algorithm for the iterative orbital update in complete active space self‐consistent‐field (CASSCF) calculations is presented. Following Angeli et al. (J. Chem. Phys. 2002, 117, 10525), the first‐order contribution of singly excited configurations to the CASSCF wave function is evaluated using the Dyall Hamiltonian for the determination of a zeroth‐order Hamiltonian. These authors employ an iterative diagonalization of the first‐order density matrix including the first‐order correction arising from single excitations, whereas the present approach uses the single‐excitation amplitudes directly for the construction of the exponential of an anti‐Hermitian matrix resulting in a unitary matrix which can be used for the orbital update. At convergence, the single‐excitation amplitudes vanish as a consequence of the generalized Brillouin's theorem. It is shown that this approach in combination with direct inversion of the iterative subspace (DIIS) leads to very rapid convergence of the CASSCF iteration procedure. © 2019 Wiley Periodicals, Inc.