A1 Refereed original research article in a scientific journal
Machine learning in interpretation of electronic core-level spectra
Authors: Niskanen Johannes, Vladyka Anton, Kettunen J. Antti, Sahle Christoph
Publisher: Elsevier
Publication year: 2022
Journal: Journal of Electron Spectroscopy and Related Phenomena
Journal acronym: Journal of Electron Spectroscopy and Related Phenomena
Article number: 147243
Volume: 260
Issue: 147243
eISSN: 1873-2526
DOI: https://doi.org/10.1016/j.elspec.2022.147243
Web address : https://doi.org/10.1016/j.elspec.2022.147243
Self-archived copy’s web address: https://research.utu.fi/converis/portal/detail/Publication/176024642
Preprint address: https://arxiv.org/abs/2104.02374v1
Electronic transitions involving core-level orbitals offer a localized, atomic-site and element specific peek window into statistical systems such as molecular liquids. Although formally understood, the complex relation between structure and spectrum -- and the effect of statistical averaging of highly differing spectra of individual structures -- render the analysis of an ensemble-averaged core-level spectrum complicated. We explore the applicability of machine learning for molecular structure -- core-level spectrum interpretation. We focus on the electronic Hamiltonian using the \ce{H2O} molecule in the classical-nuclei approximation as our test system. For a systematic view we studied both predicting structures from spectra and, vice versa, spectra from structures, using polynomial approaches and neural networks. We find predicting spectra easier than predicting structures, where a tighter grid (even unphysical) of the spectrum improves prediction, possibly inviting for over-interpretation of the model. The accuracy of the structure prediction worsens when moving outwards from the center of mass of the training set in the structural parameter space, which can not be overcome by model selection based on generalizability.
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