氢原子在Ni(111)次表面和Ni(211)、(533)台阶面上的吸附与振动

应用原子与表面簇合物相互作用的五参数Morse势(5-MP)方法对氢原子在Ni(111)表面和次表面以及Ni(211), (533)台阶面进行了系统研究, 得到了氢原子在上述各面的吸附位、吸附几何、结合能和本征振动频率. 计算结果表明, 在Ni(111)面上, 氢原子优先吸附在三重位, 随着覆盖度的增加会吸附在次表面八面体位和四面体位. Ni(211), (533)的最优先吸附位都是四重位, 当氢原子的覆盖度增大时占据(111)平台的三重吸附位. 靠近台阶面的吸附位受台阶和平台高度的影响很大. 此外, 我们计算了氢原子在各表面的不同吸附位的扩散势垒, 获得氢原子在各表面的最低能量扩散通道.

Adsorption and Vibration of Hydrogen Atom on Ni(111)Subsurface and Ni(211),(533)Stepped Surfaces

The adsorption of H atoms on Ni(111) subsurface, Ni(211) and Ni(533) stepped surfaces was investigated by using the 5-parameter Morse potential (5-MP) of interaction between an adatom and a metal surface cluster. The adsorption sites, adsorption geometry, binding energy, and eigenvibrational frequencies of H—Ni systems were obtained. On the Ni(111) surface at low coverage, H atoms are adsorbed preferably on threefold hollow sites; with the coverage increasing, H atoms occupy the subsurface octahedral sites and tetrahedral sites. On the stepped surfaces Ni(211) and Ni(533), H atoms are adsorbed preferably on the fourfold hollow sites at low coverage; with the coverage increasing, the H atoms also occupy on the threefold hollow sites of the (111) terrace. The threefold sites near the fourfold sites are strongly affected by the height of the step and terrace. Moreover, the diffusion barriers of H atom were calculated to obtain the lowest energy pathway of diffusion on the surfaces.