Abstract Hydrogen segregation to vacancies in the surface and subsurface layers of (111) and (100) surfaces of Pd is studied in the density functional theory (DFT) approach. Adsorption energies and configurations of various clusters of H atoms at the vacancies are calculated. The adsorption energy varies for different sites in the vacancies with the distance to the surface from −0.26 eV (close to that of the bulk clusters) to −0.62 eV. Enhanced binding is found for the sites above the pores produced by vacancies in the subsurface layer. For the (111) surface vacancy the most favorable for segregation are tetrahedral lattice sites, while for (100) octa-sites have higher binding energy. Lattice relaxation effects are minor for the (111) surface but noticeably enhanced for the (100) surface. Hydrogen segregation to surface layer vacancies is accompanied with minimal charge transfer, which shows itself in cluster configurations. At high surface coverage the reduction of the cluster formation energy due to the H segregation should result in strongly enlarged concentration of the subsurface vacancy clusters, while the surface remains undamaged due to the prevailing surface adsorption.

中文翻译：

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在 Pd 的低指数表面的表面和亚表面空位处捕获氢

摘要 采用密度泛函理论 (DFT) 方法研究了氢偏析到 Pd (111) 和 (100) 表面的表面和亚表面层中的空位。计算空位处各种 H 原子簇的吸附能和构型。空位中不同位点的吸附能随到表面的距离从-0.26 eV（接近体簇的）到-0.62 eV 变化。在由地下层中的空位产生的孔上方的位点发现了增强的结合。对于（111）表面空位最有利于偏析的是四面体晶格位点，而对于（100）八位点具有更高的结合能。(111) 表面的晶格弛豫效应较小，但 (100) 表面的晶格弛豫效应显着增强。氢偏析到表面层空位伴随着最小的电荷转移，这在簇配置中表现出来。在高表面覆盖率下，由于 H 偏析导致团簇形成能的降低会导致亚表面空位团簇的浓度大大增加，而由于普遍的表面吸附，表面保持未损坏。