Ab initio Thermochemistry and Kinetics of Molecules with Coupled Large-Amplitude Motions
Final Report Abstract
Major fields of energy and chemical engineering benefit from the analysis and prediction capabilities of chemical models that rely on thermochemical and kinetic data. These data are often hard or expensive to determine experimentally; if this is the case, data for modelling comes preferably from theoretical (e.g. ab initio) methods. The accurate theoretical determination of thermochemical properties requires an accurate description of both the electrons and nuclei of molecules. Nowadays, electronic structure methods can provide electronic energies with an uncertainty on the order of 1 kJ/mol. By contrast, the motion of the nuclei — especially in case of coupled anharmonic motion — is often described with an uncertainty rather on the order of 10 kJ/mol. This project aimed at overcoming this bottleneck by applying new exact and systematically approximated formulations of the Hamilton operator for the nuclei and solving the Schrödinger Equation with a variational approach. During the project, we developed new ways to model intraand intermolecular potential energy surfaces with functions that allow for the analytical evaluation of the Hamilton matrix elements in our formulations. These new ways are simultaneously more data efficient and are more automated than previous approaches. We have implemented the formulations in software code that was then applied and validated to / by model systems and small molecules. The results show the potential of the method, but they also show that more work is needed to make it applicable for the development of chemical models for most molecular systems of practical interest.
Publications
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Improved modeling of anharmonicity for furan microsolvation. Physical Chemistry Chemical Physics, 25(16), 11316-11323.
Kopp, Wassja A.; Mödden, Matthias L.; Viswanathan, Narasimhan; Rath, Gabriel & Leonhard, Kai
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The first HyDRA challenge for computational vibrational spectroscopy. Physical Chemistry Chemical Physics, 25(33), 22089-22102.
Fischer, Taija L.; Bödecker, Margarethe; Schweer, Sophie M.; Dupont, Jennifer; Lepère, Valéria; Zehnacker-Rentien, Anne; Suhm, Martin A.; Schröder, Benjamin; Henkes, Tobias; Andrada, Diego M.; Balabin, Roman M.; Singh, Haobam Kisan; Bhattacharyya, Himangshu Pratim; Sarma, Manabendra; Käser, Silvan; Töpfer, Kai; Vazquez-Salazar, Luis I.; Boittier, Eric D.; Meuwly, Markus ... & Mata, Ricardo A.
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Efficient Generation of Torsional Energy Profiles by Multifidelity Gaussian Processes for Hindered Rotor Corrections. Journal of Chemical Theory and Computation, 20(17), 7574-7585.
Fleck, Maximilian; Kopp, Wassja A.; Viswanathan, Narasimhan; Hansen, Niels; Gross, Joachim & Leonhard, Kai
