The formation and migration of AlH₃ defect is suggested to be the rate-limiting step in the early stage of the dehydrogenation of NaAlH₄. This paper presents a first-principles calculations on studying the formation and migration of AlH₃ defect in (1 1 2) NaAlH₄ surface. We find that AlH₃ defect tends to be formed closer to the surface, in particular in the top layer. The AlH₅²⁻ unit, which is suggested as a precursor of the dehydrogenation, is formed preferably in the second layer. The reorientation of AlH₅²⁻ unit results in the complete diffusion of AlH₃ defect. The migration of AlH₃ defect along (1 1 2) surface is an exothermic process, yielding a barrier of 0.38 eV.

AlH ₃缺陷的形成和迁移被认为是NaAlH ₄脱氢早期的限速步骤。本文提出了关于研究（1 1 2）NaAlH ₄表面中AlH ₃缺陷的形成和迁移的第一性原理计算。我们发现，AlH ₃缺陷倾向于靠近表面形成，特别是在顶层。被建议作为脱氢的前体的AlH ₅ ^2-单元优选在第二层中形成。AlH ₅ ^2-单元的重新取向导致AlH ₃缺陷的完全扩散。AlH ₃的迁移 沿（1 1 2）表面的缺陷是一个放热过程，产生0.38 eV的势垒。