ET类分子导体3d轨道对晶体能带及导电性的影响

Influence of 3d Orbital on the Energy Band and Electrical Conductivity in ET-type Molecular Conductor

采用扩展休克尔 -紧束缚方法 (EHTB)研究了ET类分子导体 [ET =bis (ethylenedithio) tetrathiafulvalene]的能带 .讨论了硫原子 3d轨道对能带结构的影响 ,添加 3d轨道导致ET分子柱间的横向作用大为增强 ,并与纵向作用处于同一数量级 ,这一结论解释了晶体二维导电性的实验结果 .计算得到 (ET) 2 C3 H5SO3 ·H2 O ,(ET) 2 HgCl3 ·TCE两个晶体的带隙分别为0 5 79,0 .5 72eV ,与实验得到的导电激活能 0 .3 19,0 .3 0 8eV符合较好 .

Energy band of ET-type molecular conductors were calculated using the Extended Hückel-Tight Binding method (EHTB). The introducing of sulfur 3d orbitals to the EHTB calculation leads to a great enhancement of the transverse interactions between ET stacks. Consequently, the transverse and longitudinal interactions in the ET stacks have the same order of magnitude. The results could well explain the two-dimensional conductivity nature of this kind of molecular conductors. Calculated band gaps of the (ET) 2C 3H 5SO 3·H 2O and (ET) 2HgCl 3·TCE crystals are 0.579 and 0.572 eV respectively, which were in good agreement with the experimental conductive activation energy 0.319 and 0.308 eV.