TY - JOUR A1 - Haack, Fiete A1 - Röblitz, Susanna A1 - Scharkoi, Olga A1 - Schmidt, Burkhard A1 - Weber, Marcus T1 - Adaptive Spectral Clustering for Conformation Analysis JF - AIP Conference Proceedings Y1 - 2010 UR - http://link.aip.org/link/?APC/1281/1585/1 U6 - https://doi.org/10.1063/1.3498116 VL - 1281 IS - 1 SP - 1585 EP - 1588 PB - AIP ER - TY - JOUR A1 - Schäfer-Bung, B. A1 - Hartmann, Carsten A1 - Schmidt, Burkhard A1 - Schütte, Christof T1 - Dimension reduction by balanced truncation JF - J. Chem. Phys. Y1 - 2011 UR - http://publications.imp.fu-berlin.de/1023/ VL - 135 IS - 1 SP - 014112 ER - TY - JOUR A1 - Marsalek, Ondrej A1 - Frigato, Tomaso A1 - VandeVondele, Joost A1 - Bradforth, Stephen E. A1 - Schmidt, Burkhard A1 - Schütte, Christof A1 - Jungwirth, Pavel T1 - Hydrogen Forms in Water by Proton Transfer to a Distorted Electron JF - J. Phys. Chem. B Y1 - 2010 UR - http://publications.imp.fu-berlin.de/818/ U6 - https://doi.org/10.1021/jp908986z VL - 114 IS - 2 SP - 915 EP - 920 ER - TY - JOUR A1 - Frigato, Tomaso A1 - VandeVondele, Joost A1 - Schmidt, Burkhard A1 - Schütte, Christof A1 - Jungwirth, Pavel T1 - Ab Initio Molecular Dynamics Simulation of a Medium-Sized Water Cluster Anion JF - J. Phys. Chem. A Y1 - 2008 UR - http://publications.imp.fu-berlin.de/13/ U6 - https://doi.org/10.1021/jp711545s VL - 112 IS - 27 SP - 6125 EP - 6133 ER - TY - JOUR A1 - Antony, Jens A1 - Schmidt, Burkhard A1 - Schütte, Christof T1 - Nonadiabatic Effects on Peptide Vibrational Dynamics Induced by Conformational Changes JF - J. Chem. Phys. Y1 - 2005 UR - http://publications.imp.fu-berlin.de/57/ U6 - https://doi.org/10.1063/1.1829057 VL - 122 IS - 1 SP - 014309 ER - TY - JOUR A1 - Horenko, Illia A1 - Weiser, Martin A1 - Schmidt, Burkhard A1 - Schütte, Christof T1 - Fully Adaptive Propagation of the Quantum-Classical Liouville Equation JF - J. Chem. Phys. Y1 - 2004 UR - http://publications.imp.fu-berlin.de/65/ U6 - https://doi.org/10.1063/1.1691015 VL - 120 IS - 19 SP - 8913 EP - 8923 ER - TY - CHAP A1 - Meerbach, E. A1 - Schütte, Christof A1 - Horenko, Illia A1 - Schmidt, Burkhard ED - Kühn, O. ED - Wöste, L. T1 - Metastable Conformational Structure and Dynamics T2 - Analysis and Control of Ultrafast Photoinduced Reactions Y1 - 2007 UR - http://publications.imp.fu-berlin.de/114/ U6 - https://doi.org/10.1007/978-3-540-68038-3_9 VL - 87 SP - 796 EP - 806 PB - Springer CY - Berlin ER - TY - JOUR A1 - Nettesheim, Peter A1 - Bornemann, Folkmar A. A1 - Schmidt, Burkhard A1 - Schütte, Christof T1 - An Explicit and Symplectic Integrator for Quantum-Classical Molecular Dynamics JF - Chem. Phys. Lett. Y1 - 1996 UR - http://publications.imp.fu-berlin.de/101/ U6 - https://doi.org/10.1016/0009-2614(96)00471-X VL - 256 IS - 6 SP - 581 EP - 588 ER - TY - JOUR A1 - Horenko, Illia A1 - Schmidt, Burkhard A1 - Schütte, Christof T1 - Multidimensional Classical Liouville Dynamics with Quantum Initial Conditions JF - J. Chem. Phys. Y1 - 2002 UR - http://publications.imp.fu-berlin.de/73/ U6 - https://doi.org/10.1063/1.1498467 VL - 117 IS - 10 SP - 4643 EP - 4650 ER - TY - JOUR A1 - Horenko, Illia A1 - Salzmann, Ch. A1 - Schmidt, Burkhard A1 - Schütte, Christof T1 - Quantum-Classical Liouville Approach to Molecular Dynamics JF - J. Chem. Phys. Y1 - 2002 UR - http://publications.imp.fu-berlin.de/75/ U6 - https://doi.org/10.1063/1.1522712 VL - 117 IS - 24 SP - 11075 EP - 11088 ER - TY - JOUR A1 - Horenko, Illia A1 - Schmidt, Burkhard A1 - Schütte, Christof T1 - A Theoretical Model for Molecules Interacting with Intense Laser Pulses JF - J. Chem. Phys. Y1 - 2001 UR - http://publications.imp.fu-berlin.de/79/ U6 - https://doi.org/10.1063/1.1398577 VL - 115 IS - 13 SP - 5733 EP - 5743 ER - TY - JOUR A1 - Haack, Fiete A1 - Fackeldey, Konstantin A1 - Röblitz, Susanna A1 - Scharkoi, Olga A1 - Weber, Marcus A1 - Schmidt, Burkhard T1 - Adaptive spectral clustering with application to tripeptide conformation analysis JF - The Journal of Chemical Physics Y1 - 2013 U6 - https://doi.org/10.1063/1.4830409 VL - 139 SP - 110 EP - 194 ER - TY - GEN A1 - Schmidt, Burkhard A1 - Zdanska, Petra T1 - Solution of the Time-Dependent Schroedinger Equation for Highly Symmetric Potentials N2 - The method of symmetry adapted wavepackets (SAWP) to solve the time-dependent Schrödinger equation for a highly symmetric potential energy surface is introduced. The angular dependence of a quantum-mechanical wavepackets is expanded in spherical harmonics where the number of close-coupled equations for the corresponding radial functions can be efficiently reduced by symmetry adaption of the rotational basis using the SWAP approach. Various techniques to generate symmetry adapted spherical harmonics (SASHs) for the point groups of highest symmetry (octahedral, icosahedral) are discussed. The standard projection operator technique involves the use of Wigner rotation matrices. Two methods to circumvent numerical instabilities occuring for large azimuthal quantum numbers are suggested. The first is based on a numerical scheme which employs Gaussian integrations yielding exact and stable results. The second is a recursive algorithm to generate higher order SASHs accurately and efficiently from lower order ones. The paper gives a complete set of ``seed functions'' generated by projection techniques which can be used obtain SASHs for all irreducible representations of the octahedral and icosahedral point groups recursively. T3 - ZIB-Report - SC-99-11 KW - Schroedinger Equation KW - quantum mechanics KW - symmetry KW - group theory Y1 - 1999 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-3996 ER - TY - GEN A1 - Backhaus, Peter A1 - Schmidt, Burkhard A1 - Dantus, Marcos T1 - Control of photoassociation yield: A quantum-dynamical study of the mercury system to explore the role of pulse duration from nanoseconds to femtoseconds N2 - The photoassociation process shows strong dependence on the temporal duration of the electromagnetic field pulses and their frequencies. This dependence is investigated using quantum mechanical simulations that include all ranges of impact parameters and contributions from bound-to-bound transitions. The photoassociation yield of mercury atoms to produce excimer dimers is enhanced for short (ps) and for ultrashort (fs) pulse durations. Ultrashort laser pulses effectively overlap the entire range of free-to-bound transition, therefore achieving a maximum probability. Short pulses show a maximum in the photoassociation yield when their carrier frequency overlaps a particular free-to-bound spectroscopic resonance. Implications of these calculations on efforts to control bimolecular reactions are discussed. T3 - ZIB-Report - SC-99-12 KW - photoassociation KW - laser pulse control Y1 - 1999 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0297-zib-4001 ER - TY - CHAP A1 - Schembera, Björn A1 - Wübbeling, Frank A1 - Kleikamp, Hendrik A1 - Schmidt, Burkhard A1 - Shehu, Aurela A1 - Reidelbach, Marco A1 - Biedinger, Christine A1 - Fiedler, Jochen A1 - Koprucki, Thomas A1 - Iglezakis, Dorothea A1 - Göddeke, Dominik T1 - Towards a Knowledge Graph for Models and Algorithms in Applied Mathematics T2 - Metadata and Semantic Research. MTSR 2024 N2 - Mathematical models and algorithms are an essential part of mathematical research data, as they are epistemically grounding numerical data. To make this research data FAIR, we present how two previously distinct ontologies, MathAlgoDB for algorithms and MathModDB for models, were merged and extended into a living knowledge graph as the key outcome. This was achieved by connecting the ontologies through computational tasks that correspond to algorithmic tasks. Moreover, we show how models and algorithms can be enriched with subject-specific metadata, such as matrix symmetry or model linearity, essential for defining workflows and determining suitable algorithms. Additionally, we propose controlled vocabularies to be added, along with a new class that differentiates base quantities from specific use case quantities. We illustrate the capabilities of the developed knowledge graph using two detailed examples from different application areas of applied mathematics, having already integrated over 250 research assets into the knowledge graph. Y1 - 2025 SN - 9783031819735 U6 - https://doi.org/10.1007/978-3-031-81974-2_8 SN - 1865-0929 VL - 2331 SP - 95 EP - 109 PB - Springer Nature Switzerland CY - Cham ER - TY - JOUR A1 - Gelß, Patrick A1 - Klein, Rupert A1 - Matera, Sebastian A1 - Schmidt, Burkhard T1 - Quantum dynamics of coupled excitons and phonons in chain-like systems: tensor train approaches and higher-order propagators JF - The Journal of Chemical Physics Y1 - 2025 U6 - https://doi.org/10.1063/5.0258904 VL - 162 ER - TY - CHAP A1 - Schembera, Björn A1 - Wübbeling, Frank A1 - Kleikamp, Hendrik A1 - Biedinger, Christine A1 - Fiedler, Jochen A1 - Reidelbach, Marco A1 - Shehu, Aurela A1 - Schmidt, Burkhard A1 - Koprucki, Thomas A1 - Iglezakis, Dotothea A1 - Göddeke, Dominik T1 - Ontologies for Models and Algorithms in Applied Mathematics and Related Disciplines T2 - Metadata and Semantic Research - MTSR 2023 N2 - In applied mathematics and related disciplines, the modeling-simulation-optimization workflow is a prominent scheme, with mathematical models and numerical algorithms playing a crucial role. For these types of mathematical research data, the Mathematical Research Data Initiative has developed, merged and implemented ontologies and knowledge graphs. This contributes to making mathematical research data FAIR by introducing semantic technology and documenting the mathematical foundations accordingly. Using the concrete example of microfracture analysis of porous media, it is shown how the knowledge of the underlying mathematical model and the corresponding numerical algorithms for its solution can be represented by the ontologies. Y1 - 2023 U6 - https://doi.org/10.1007/978-3-031-65990-4_14 SP - 161 EP - 168 PB - Springer Nature Switzerland CY - Cham ET - Communications in Computer and Information Science ER - TY - JOUR A1 - Schembera, Björn A1 - Wübbeling, Frank A1 - Koprucki, Thomas A1 - Biedinger, Christine A1 - Reidelbach, Marco A1 - Schmidt, Burkhard A1 - Göddeke, Dominik A1 - Fiedler, Jochen T1 - Building Ontologies and Knowledge Graphs for Mathematics and its Applications JF - Proceedings of the Conference on Research Data Infrastructure N2 - Ontologies and knowledge graphs for mathematical algorithms and models are presented, that have been developed by the Mathematical Research Data Initiative. This enables FAIR data handling in mathematics and the applied disciplines. Moreover, challenges of harmonization during the ontology development are discussed. Y1 - 2023 U6 - https://doi.org/10.52825/cordi.v1i.255 SN - 2941-296X VL - 1 PB - TIB Open Publishing ER - TY - JOUR A1 - Riedel, Jerome A1 - Gelß, Patrick A1 - Klein, Rupert A1 - Schmidt, Burkhard T1 - WaveTrain: a Python Package for Numerical Quantum Mechanics of Chain-like Systems Based on Tensor Trains JF - The Journal of Chemical Physics N2 - WaveTrain is an open-source software for numerical simulations of chain-like quantum systems with nearest-neighbor (NN) interactions only. The Python package is centered around tensor train (TT, or matrix product) format representations of Hamiltonian operators and (stationary or time-evolving) state vectors. It builds on the Python tensor train toolbox Scikit_tt, which provides efficient construction methods and storage schemes for the TT format. Its solvers for eigenvalue problems and linear differential equations are used in WaveTrain for the time-independent and time-dependent Schrödinger equations, respectively. Employing efficient decompositions to construct low-rank representations, the tensor-train ranks of state vectors are often found to depend only marginally on the chain length N. This results in the computational effort growing only slightly more than linearly with N, thus mitigating the curse of dimensionality. As a complement to the classes for full quantum mechanics, WaveTrain also contains classes for fully classical and mixed quantum–classical (Ehrenfest or mean field) dynamics of bipartite systems. The graphical capabilities allow visualization of quantum dynamics “on the fly,” with a choice of several different representations based on reduced density matrices. Even though developed for treating quasi-one-dimensional excitonic energy transport in molecular solids or conjugated organic polymers, including coupling to phonons, WaveTrain can be used for any kind of chain-like quantum systems, with or without periodic boundary conditions and with NN interactions only. The present work describes version 1.0 of our WaveTrain software, based on version 1.2 of scikit_tt, both of which are freely available from the GitHub platform where they will also be further developed. Moreover, WaveTrain is mirrored at SourceForge, within the framework of the WavePacket project for numerical quantum dynamics. Worked-out demonstration examples with complete input and output, including animated graphics, are available. Y1 - 2023 U6 - https://doi.org/10.1063/5.0147314 VL - 158 IS - 16 SP - 164801 ER - TY - JOUR A1 - Gelß, Patrick A1 - Klein, Rupert A1 - Matera, Sebastian A1 - Schmidt, Burkhard T1 - Solving the time-independent Schrödinger equation for chains of coupled excitons and phonons using tensor trains JF - The Journal of Chemical Physics N2 - We demonstrate how to apply the tensor-train format to solve the time-independent Schrödinger equation for quasi-one-dimensional excitonic chain systems with and without periodic boundary conditions. The coupled excitons and phonons are modeled by Fröhlich–Holstein type Hamiltonians with on-site and nearest-neighbor interactions only. We reduce the memory consumption as well as the computational costs significantly by employing efficient decompositions to construct low-rank tensor-train representations, thus mitigating the curse of dimensionality. In order to compute also higher quantum states, we introduce an approach that directly incorporates the Wielandt deflation technique into the alternating linear scheme for the solution of eigenproblems. Besides systems with coupled excitons and phonons, we also investigate uncoupled problems for which (semi-)analytical results exist. There, we find that in the case of homogeneous systems, the tensor-train ranks of state vectors only marginally depend on the chain length, which results in a linear growth of the storage consumption. However, the central processing unit time increases slightly faster with the chain length than the storage consumption because the alternating linear scheme adopted in our work requires more iterations to achieve convergence for longer chains and a given rank. Finally, we demonstrate that the tensor-train approach to the quantum treatment of coupled excitons and phonons makes it possible to directly tackle the phenomenon of mutual self-trapping. We are able to confirm the main results of the Davydov theory, i.e., the dependence of the wave packet width and the corresponding stabilization energy on the exciton–phonon coupling strength, although only for a certain range of that parameter. In future work, our approach will allow calculations also beyond the validity regime of that theory and/or beyond the restrictions of the Fröhlich–Holstein type Hamiltonians. Y1 - 2022 U6 - https://doi.org/10.1063/5.0074948 VL - 156 IS - 2 SP - 024109 ER -