Effects of local and gradient-corrected density approximations on the prediction of the intralayer lattice distance c, in graphite and LiC6

被引:18
作者
Kganyago, KR
Ngoepe, PE [1 ]
机构
[1] Univ North, Mat Modelling Ctr, ZA-0727 Sovenga, South Africa
[2] CSIR, Div Mat Sci & Technol, ZA-0001 Pretoria, South Africa
关键词
graphite; LiC6; LDA; GGA; structural; charge density;
D O I
10.1080/08927029908022085
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
Ab initio total energy calculations, on hexagonal models of graphite and LiC6, are carried out within the most widely density functional theory (DFT) implementation, the local density approximation (LDA). Improvements to LDA in the form of generalized gradient approximation (GGA) are explored. Structural parameters predicted by LDA, as expected underestimate experiment within 1-2% margin of accuracy. GGA does not give a good account in the prediction of lattice parameter c, especially in graphite. This is evident in both recently implemented gradient corrections by Perdew and Wang and earlier corrections by Becke approximations. A substantial improvement is seen on introducing lithium ion in LiC6 and using recent approximations. Valence electron densities from both LDA and GGA calculations, shows charge distribution plots that compare well with experimental results. Charge density distribution plots of these approximations appears similar on a larger scale.
引用
收藏
页码:39 / +
页数:15
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