Department of Applied Physics, University of Electronic Science and Technology of China, Chengdu 610054, People's Republic of China.
J Phys Condens Matter. 2011 Jan 26;23(3):035701. doi: 10.1088/0953-8984/23/3/035701. Epub 2011 Jan 5.
Ab initio calculations based on density functional theory have been performed to determine the relative stabilities and migration of H and He atoms in hcp-Sc. The results show that the formation energy of an interstitial H or He atom is smaller than that of a corresponding substitutional atom. The tetrahedral (T) interstitial position is more stable than an octahedral (O) position for both He and H interstitials. The nudged elastic band method has been used to study the migration of interstitial H and He atoms in hcp-Sc. It is found that the migration energy barriers for H interstitials in hcp-Sc are significantly different from those for He interstitials, but their migration mechanisms are similar. In addition, the formation energies of five different configurations of a H-H pair were determined, revealing that the most stable configuration consists of two H atoms located at the second-neighbor tetrahedral interstitial sites along the hexagonal direction. The formation and relative stabilities of some small He clusters have also been investigated.
基于密度泛函理论的从头算方法被用来确定 H 和 He 原子在 hcp-Sc 中的相对稳定性和迁移。结果表明，间隙 H 或 He 原子的形成能小于相应的替位原子。对于 He 和 H 间隙原子，四面体（T）间隙位置比八面体（O）位置更稳定。用推斥弹性带方法研究了 hcp-Sc 中间隙 H 和 He 原子的迁移。发现 hcp-Sc 中 H 间隙原子的迁移能垒与 He 间隙原子显著不同，但它们的迁移机制相似。此外，还确定了 H-H 对的五种不同构型的形成能，表明最稳定的构型由两个 H 原子组成，它们位于沿六方方向的第二近邻四面体间隙位置。还研究了一些小 He 团簇的形成和相对稳定性。
