Ce在Si(111)面上吸附的EHT研究方法

采用集团模型和半经验的EHT方法研究Ce原子在Si(111)顶位和三度位吸附,由体系总能量最低确定了稳定的吸附位置,并在最稳定的三度吸附位讨论了Ce-Si成键特性和状态密度.结果表明,Ce原子的5d和4f轨道与Si原子的3p轨道相互作用,在费米能级以下形成了混杂的能级,同时5d和4f轨道的能量降低,获得少量6s轨道的电荷,而整个Ce原子失去约0.8个电子.计算所得结果及态密度在吸附前后的变化与第一性原理的DVM计算符合较好.

An Extended Huckel Study of Ce/Si(111) Chemisorption

Semiempirical EHT method is used in studying the chemisorption of rare earth Ce on Sl(111).Cluster models are used to simulate two possible sites-the top site and the threefold site.The latter is found to be more stable than the former.The optimized vertical dis-tance between Ce and the surface is obtained as 4.0 a.u. on the three-fold hollow site, whichagrees very well with the result of the first principle DVM calculation.The energy shift ofvalence levels and the charge transfer are alsc in good agreement with the results of DVM.This provides a simple and flexible method to study the problem.