Structures and energetics of multiple helium atoms in a tungsten monovacancy

C Song and J Hou and XS Kong and L Chen and SK Wang and C Liu, JOURNAL OF NUCLEAR MATERIALS, 561, 153577 (2022).

DOI: 10.1016/j.jnucmat.2022.153577

Helium exposure is known to induce severe damages in tungsten materials, which are often linked with the aggregation of helium at vacancies. Yet even for the simplest case of monovacancies, a complete atomistic understanding of helium aggregation is not available, with relevant structures and energetics being largely uncharted and contended. Here, starting with comprehensive ab initio molecular dynamics (AIMD) simulations, we systematically investigated helium aggregation in a tungsten monovacancy (Vac-He-n with n = 1-13), revealed the spatial distribution and correlations for helium atoms. A great number of structures, constructed by manual helium insertion based on empirical knowledge or extracted randomly from the AIMD trajectories, were then examined with density functional theory minimizations to identify the most stable ones. These calculations provide reliable structures and energies for Vac-He-n clusters, thus were used as critical benchmarks to evaluate five commonly used tungsten-helium empirical potentials. This work presents accurate atomistic insights toward helium aggregation in a tungsten monovacancy, offering a reliable reference for selecting interatomic potentials to simulate helium induced damages. (c) 2022 Elsevier B.V. All rights reserved.

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