AutoCheMo - Automatic Generation of Chemical Models

 

The Automatic generation of Chemical Models (AutoCheMo) project was a three-year cooperation with the Center for Molecular Modeling at Ghent University and the industrial partner Software for Chemistry & Materials in Amsterdam.

So far, post-processing of MD trajectories was lacking a concise representation of results for very large reaction networks. Also, the generation of a suitable set of empirical parameters for ReaxFF is time and resource consuming, as it requires large but accurate training sets containing a variety of stable and unstable species. With the combination of MD and QM refinement, the ChemTraYzer provides a framework for the automatization of the parametrization process.

Both the representation of results and the automatization of the force-field parametrization were addressed in the EU-funded project AutoCheMo.

 

Another goal in the AutoCheMo project was going beyond the commonly used harmonic oscillator approximation in QM calculations by considering coupled anharmonic motions to improve the accuracy of thermodynamic properties and reaction kinetics predictions. Nuclei move often in a complex coupled manner [1]. While methods describing the electrons are very accurate, modeling of the nuclear degrees of freedom turn out to be the bottleneck for the overall accuracy. Widely used models for nuclear motion (like the rigid-rotor harmonic-oscillator approximation) fail to describe coupled motions. In the AutoCheMo project, we developed a highly accurate computation of such coupled (and anharmonic) motions at the quantum-mechanical level. By using internal coordinates and some properties of the Jacobian [2], we develop a software that not only computes small systems with benchmark accuracy but also contains approximations for larger systems of technical interest, like biofuels [3] or solvents [4].

 

Relevant Publications

[1] Muhammad Umer und Kai Leonhard, Ab Initio Calculations of Thermochemical Properties of Methanol Clusters, The Journal of Physical Chemistry A, 2013, volume 117, issue 7, page 1569-1582.
[2] Wassja A. Kopp und Kail Leonhard, General formulation of rovibrational kinetic energy operators and matrix elements in internal bond-angle coordinates using factorized Jacobians, The Journal of Chemical Physics, 2016, volume 145, issue 23, page 234102.
[3] Leif C. Kröger, Malte Döntgen, Dzmitry Firaha, Wassja A. Kopp und Kai Leonhard, Ab initio kinetics predictions for H-atom abstraction from diethoxymethane by hydrogen, methyl, and ethyl radicals and the subsequent unimolecular reactions, Proceedings of the Combustion Institute, In Press, Corrected Proof.
[4] Hannes C. Gottschalk et. al., The furan microsolvation blind challenge for quantum chemical methods: First steps, The Journal of Chemical Physics, 2018, volume 148, issue 1, page 014301.