The energetics of Fe interstitials and their clusters as well as the effect of Fe on the migration of self-interstitial (SIA) and vacancies in vanadium (V) are investigated by first-principles calculations. We determined the formation energies of mono-/di- Fe-V and Fe-Fe interstitial pairs by typical structures (<111>, <110> and <100>), and found that the <110> and mixed <111> dumbbell are the lowest energy configuration. Secondly, we determined the formation/binding energies of small Fe-Fe/Fe-V interstitial clusters with sizes of 3–6. The binding energies of clusters increase with sizes from 0.69 to 4.62 eV. The interstitial clusters tend to form three-dimensional parallel configurations and the parallel <111> configurations are the most stable. By comparison, the <111> clusters are more stable than both mixed Fe-V and SIA clusters. Moreover, we explored the effect of Fe on the formation and migration of SIAs/vacancies. Fe increases defect formation energy and changes rotation barrier of SIA. The migration barrier of SIAs near Fe is still very small along <111> direction, and the SIAs near compressed Fe can transform into mixed Fe-V pair with a low barrier of 0.01 eV. Vacancy migrating towards Fe exhibits a higher barrier of 0.52/0.54 eV than that of 0.39 eV in pure V, while the barrier of vacancy exchanging Fe is very high of about 1.05 eV.

中文翻译：

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钒中Fe间隙团簇能量的第一性原理研究

通过第一性原理计算研究了 Fe 间隙原子及其团簇的能量学以及 Fe 对自间隙原子 (SIA) 迁移和钒 (V) 空位的影响。我们通过典型结构（<111>、<110>和<100>）测定了单/双Fe-V和Fe-Fe间隙对的形成能，发现<110>和混合<111>哑铃是最低能量配置。其次，我们确定了尺寸为 3-6 的小型 Fe-Fe/Fe-V 间隙簇的形成/结合能。簇的结合能随着尺寸从 0.69 eV 增加到 4.62 eV。间隙团簇倾向于形成三维平行构型，并且平行<111>构型是最稳定的。相比之下，<111>团簇比混合 Fe-V 团簇和 SIA 团簇更稳定。此外，我们还探讨了 Fe 对 SIA/空位形成和迁移的影响。 Fe 增加缺陷形成能并改变 SIA 的旋转势垒。 Fe附近的SIA沿<111>方向的迁移势垒仍然很小，并且压缩Fe附近的SIA可以转变为具有0.01 eV低势垒的混合Fe-V对。空位向 Fe 迁移的势垒比纯 V 中的 0.39 eV 更高，为 0.52/0.54 eV，而空位交换 Fe 的势垒非常高，约为 1.05 eV。