物理化学学报 >> 1998, Vol. 14 >> Issue (03): 198-203.doi: 10.3866/PKU.WHXB19980302

研究论文 上一篇    下一篇

TiC、TiC1-x、(Ti1-xNbx)C电子结构的计算

崔万秋, 雷鸣   

  1. 武汉工业大学材料学院，武汉 430070
  • 收稿日期:1997-06-13 修回日期:1997-09-10 发布日期:1998-03-15
  • 通讯作者: 崔万秋

Calculations for Electronic Structure of TiC、TiC1-x and (Ti1-xNbx)C

Cui Wan-Qiu, Lei Ming   

  1. Department of Material Science,Wuhan University of Technology,Wuhan 430070
  • Received:1997-06-13 Revised:1997-09-10 Published:1998-03-15
  • Contact: Cui Wan-Qiu

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摘要：

采用离散变分x_α法（DV-X_α法）对TiC理想晶体、空位和掺杂缺陷结构中的电子结构进行了计算．通过选取分子簇模型，模拟了理想晶体、空位和掺杂缺陷情况．采用多重散射离散变分X_α法，通过自治迭代来求解局域密度泛函方程，得到了各个分子簇模型的电子结构．分析计算结果发现，在理想TiC结构的态密度图中，费米能级位于两峰之间．但在费米能级处的电子态密度不为零，这提供了TiC导电性的来源．在空位模型中，发现电子态密度在费米能级处有较大的值，说明空位的存在有利于提高TiC的导电能力．对于Nb掺杂后的电子结构，在费米能级处存在一个电子态密度峰，因而也有利于提高其导电性．在计算的过程中考虑到了分子簇模型边界条件带来的电行转移效应对电子结构的影响，通过提供适当的环境势，得到了较精确的计算结果．与已有的计算结果进行了对比，有较好的一致性．

关键词: DV-Xa法, TiC分子簇, 电子结构

Abstract:

Using the discrete-variational (DV-X_α) method, the electronic structures of TiC ideal crystal, carbon vacancies and Nb doped defect structure were investigated. We used the clusters to imitate the ideal crystal, C vacancies and Nb doped defect structure. The local density functional equation was self-consistently iterated by using SCM-DV-Xα method. The Fermi level lies between the two peaks in our results, where the DOS value is not equal to zero. This suggests the origin of the conductivity of TiC. For the vacancies cluster a peak was found near the Fermi level, thus the vacancy has the advantage of improving the conductivity of TiC. We also found a small peak near the Fermi level in the case of Nb doped cluster. Doping Nb also is beneficial to the conductivity. The influence of the boundaries of the clusters on the result was taken account of in the calculation. An environmental potential was used to eliminate the charge transition. On comparing our result with those of other authors, we found our results are well consistent with the experimental results.

Key words: DV-Xa method, Molecular cluster of TiC, Electronic structure