Application of Ligand Field Theory for Simulation of the Pre-Edge Structure of X-Ray Absorption Spectra of Amorphous Systems

Autor: Sergey A. Guda, M. V. Kirichkov, Alexander A. Guda, D. S. Rubanik, Alexander V. Soldatov, D. M. Pashkov
Rok vydání: 2021
Předmět:
Zdroj: Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques. 15:1-6
ISSN: 1819-7094
1027-4510
DOI: 10.1134/s1027451021010110
Popis: The theoretical basis of X-ray absorption spectra beyond the Fe K-edge in the pre-edge region is constructed, and algorithms for using it to quantitatively analyze experimental X-ray near edge spectroscopy (XANES) spectra are described. Within the framework of the ab initio approach of ligand field theory, 60 theoretical spectra or more for Fe with different coordination numbers, oxidation state, and interatomic distances between the central atom and the nearest O atoms are calculated. Various machine learning (ML) methods for solving problems of determining the oxidation state of Fe and coordination number by means of the obtained spectra are used. The quality of the models are estimated using the Leave-One-Out method, the determination accuracy for the oxidation state is 100%; the determination accuracy for the coordination number is 75% in the case of predictions using the entire dataset and 96 and 68% for datasets with fixed oxidation state of Fe +2 and +3, respectively.
Databáze: OpenAIRE
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