期刊
AIP ADVANCES
卷 4, 期 6, 页码 -出版社
AMER INST PHYSICS
DOI: 10.1063/1.4884304
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资金
- National Magnetic Confinement Fusion Program of China [2011GB108002, 2014GB104003]
Despite well documented first-principles theoretical determination of the low migration energy (0.06 eV) of a single He in tungsten, fully quantum mechanical calculations on the migration of a He pair still present a challenge due to the complexity of its trajectory. By identifying the six most stable configurations of the He pair in W and decomposing its motion into rotational, translational, and rotational-translational routines, we are able to determine its migration barrier and trajectory. Our density functional theory calculations demonstrate a He pair has three modes of motion: a close or open circular two-dimensional motion in (100) plane with an energy barrier of 0.30 eV, a snaking motion along [001] direction with a barrier of 0.30 eV, and a twisted-ladder motion along [010] direction with the two He swinging in the plane (100) and a barrier of 0.31 eV. The graceful associative movements of a He pair are related to the chemical-bonding-like He-He interaction being much stronger than its migration barrier in W. The excellent agreement with available experimental measurements (0.24-0.32 eV) on He migration makes our first-principles result a solid input to obtain accurate He-W interatomic potentials in molecular dynamics simulations. (C) 2014 Author(s).
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