Ni(111)表面C原子吸附的密度泛函研究

基于密度泛函理论的第一性原理计算,对过渡金属Ni晶体与Ni (111)表面的结构和电子性质进行了研究, 并探讨了单个C原子在过渡金属Ni (111)表面的吸附以及两个C原子在Ni(111)表面的共吸附. 能带和态密度计算表明, Ni晶体及Ni (111)表面在费米面处均存在显著的电子自旋极化. 通过比较Ni (111)表面各位点的吸附能,发现单个C原子在该表面最稳定的吸附位置为第二层Ni原子上方所在的六角密排洞位, 吸附的第二个C原子与它形成碳二聚物时最稳定吸附位为第三层Ni原子上方所在的面心立方洞位. 电荷分析表明,共吸附时从每个C原子上各有1.566e电荷转移至相邻的Ni原子, 与单个C原子吸附时C与Ni原子间的电荷转移量(1.68e)相当. 计算发现两个C原子共吸附时在六角密排洞位和面心立方洞位的磁矩分别为0.059μ_B和 0.060μ_B,其值略大于单个C原子吸附时所具有的磁矩(0.017μ_B).

Density functional study on the adsorption of C atoms on Ni (111) surface

With the density functional first-principles calculations, we investigate the structures and electronic properties of transition metal nickel and its (111) surface. The adsorption behavior of single C atom on Ni (111) surface and its co-adsorption with the another C atom on Ni (111) surface are studied. The calculations on band structure and density of states show that significant spin polarization exists at the Fermi level of both nickel and its (111) surface. By comparing the adsorption energy, we find that the hollow site of hexagonal close-packed on the second layer of Ni atoms is the most stable position for the first C atom adsorption, and the hollow site of face-centered cubic on the third layer of Ni atoms is the most stable site for the co-adsorption of second C atom. Charge analysis shows that 1.566e charge transfers from each C atom to the adjacent Ni atom, which is similar to the 1.68e charge transfer in the first C atom adsorption case. The calculations on magnetism show that the magnetic moments of the two C atoms in co-adsorption are 0.059μ_B and 0.060μ_B, respectively, which are larger than the magnetic moment 0.017μ_B of single C atom in Ni (111) surface.