物理化学学报 >> 2006, Vol. 22 >> Issue (11): 1331-1336.doi: 10.1016/S1872-1508(06)60066-1

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LaNi5-xCox合金电子结构的第一性原理分析

李丽;吴锋;陈实;陈人杰   

  1. 北京理工大学化工与环境学院;国家高技术绿色材料发展中心, 北京 100081; 清华大学化学系, 北京 100084
  • 收稿日期:2006-04-19 修回日期:2006-06-16 发布日期:2006-11-06
  • 通讯作者: 吴锋 E-mail:wufeng863@vip.sina.com

First Principles Analysis for Electronic Structure on LaNi5-xCox Alloys

LI Li;WU Feng;CHEN Shi;CHEN Ren-Jie   

  1. School of Chemical Engineering and Environment, Beijing Institute of Technology; National Development Center of Hi-Tech Green Materials, Beijing 100081, P. R. China; Department of Chemistry, Tsinghua University, Beijing 100084, P. R. China
  • Received:2006-04-19 Revised:2006-06-16 Published:2006-11-06
  • Contact: WU Feng E-mail:wufeng863@vip.sina.com

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摘要： 基于密度泛函理论, 采用总能量计算方法与结合超软赝势平面波函数方法, 对不同Co含量的LaNi5−xCox (x=0, 0.5, 1)几何结构进行了优化, 计算了其相应的晶体结构、能带结构、态密度及Mulliken密度等, 从理论上给出了其结构参数及性质. 结果表明, 体系的价电子主要集中在费米能级EF附近, 并且随着Co含量的升高, 费米面能量单调下降. 由Mulliken密度分析可知, Ni3g—Ni3g 和Ni2c—Ni2c键的Mulliken重叠密度均降低, 说明钴取代后合金中的Ni—Ni键强减弱, 而La—Ni2c键的重叠密度值升高说明取代后合金中的La—Ni键增强.

关键词: LaNi4.5Co0.5, LaNi4Co, 电子结构, 密度泛函, 几何结构

Abstract: Electronic structures of LaNi5−xCox (x=0, 0.5, 1) hydrogen-storage alloy have been studied theoretically using the method of total energy based on the density functional theory (DFT). The plane wave function was selected as the basis set in combination with the ultrasoft pseudopotential technology. Crystal structure, energy band structure, electronic density of states, and Mulliken density of LaNi5−xCox were calculated. The results indicated that valence electrons were mainly fastened around fermi energy (EF) and EF moved toward the direction of lower energy with the increase of the Co content. According to the analysis of Mulliken overlap populations, the numerical values of the bonds between Ni3g—Ni3g and Ni2c—Ni2c decreased. It showed that Co doping let to the decrease in the bond energy between Ni—Ni. However, the values on the bond between La—Ni increased and the relevant bond energy increased.

Key words: LaNi4.5Co0.5, LaNi4Co, Electronic structure, Density functional theory, Geometrical structure