所属:Applied Engineering Physics, Department of Precision Science and Technology, Graduate School of Engineering, Osaka University
概要:Hydrogen boride (HB) sheet is a recently synthesized material characterized by a hexagonal boron ring and hydrogen at bridge site in a 1:1 H:B stoichiometric ratio. High temperature treatments, common in recent experimental setups, induce hydrogen desorption of up to 50 at% from HB sheets, altering their pristine state. Understanding these desorption processes is crucial for accurate theoretical simulations. To address this, we employed the machine learning enhanced global optimization algorithm via the GOFEE (Global Optimization with First-Principles Energy Expression) package. Through on-the-fly training on density functional theory (DFT) data, a Gaussian process regression model expedites the simulation process while maintaining accuracy. We investigated vacancy saturation levels ranging from 0 to 40 at%, generating a comprehensive set of structure minima. Spectral graph descriptor-based duplicate removal and precise DFT optimization refined the results, yielding the global minima structures for each saturation level. Analysis revealed that HB sheet stability decreases with increases saturation level, as expected. Notably, the transition from 0 to 11 at% desorption caused a significant 2 eV decrease in stability (<1 eV in other steps), indicating the initial desorption as the most challenging step. In conclusion, our study identified the most stable structures for various saturation levels, facilitating more accurate simulations for specific reactions involving HB sheets.
論文掲載,発表実績:
(学術雑誌掲載論文)
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Kurt Irvin M. Rojas, Yoshitada Morikawa, and Ikutaro Hamada,
“Structures of hydrogen boride sheets with increasing hydrogen vacancy concentration”, 2024, (in-preparation).
Posted : 2024年03月31日