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MP: Fachverband Theoretische und Mathematische Grundlagen der Physik
MP 5: Theoretical Aspects of Condensed Matter I
MP 5.4: Talk
Monday, March 18, 2024, 17:00–17:20, HL 102
Autonomous atomic Hamiltonian construction and active sampling of X-ray absorption spectroscopy by adversarial bayesian optimization — •Yixuan Zhang1, Ruiwen Xie1, Teng Long2, Damian Günzing3, Heiko Wende3, Katharina J.ollefs3, and Hongbin Zhang1 — 1Institute of Materials Science, Technical University of Darmstadt, 64287, Darmstadt, Germany — 2School of Materials Science and Engineering, Shandong University, 250061, Jinan, China — 3Faculty of Physics, University of Duisburg-Essen, 47057, Duisburg, Germany
X-ray absorption spectroscopy (XAS) is a well-established method for in-depth characterization of electronic structure. In practice hundreds of energy-points should be sampled during the measurements, and most of them are redundant. Additionally, it is also tedious to estimate reasonable parameters in the atomic Hamiltonians for mechanistic understanding. We implement an Adversarial Bayesian Optimization (ABO) algorithm comprising two coupled BOs to automatically fit the many-body model Hamiltonians and to sample effectively based on active learning (AL). Taking NiO as an example, we find that less than 30 sampling points are sufficient to recover the complete XAS with the corresponding crystal field and charge transfer models, which can be selected based on intuitive hypothesis learning. Further applications on the experimental XAS spectra reveal that less than 80 sampling points give reasonable XAS and reliable atomic model parameters. Our ABO algorithm has a great potential for future applications on automated physics-driven XAS analysis and AL sampling.
Keywords: Active learning; Atomic hamiltonian; Bayesian optimization; X-ray absorption spectroscopy