Electron-vibration coupling constants in positively charged fullerene
Electron-vibration coupling constants in positively charged fullerene
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DOI：
10.1080/13642810110062663
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发表时间：
2001-04
期刊：
影响因子：
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通讯作者：
N. Manini;A. Dal Corso;M. Fabrizio;E. Tosatti
中科院分区：
文献类型：
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作者：
N. Manini;A. Dal Corso;M. Fabrizio;E. Tosatti
最近的实验表明，C_（60）可以进行正场掺杂。在该状态下，富勒烯表现出比相应的负掺杂状态更高的电阻率和更高的超导温度。一个强的分子内空穴-声子耦合，与孤立的正离子的Jahn-Teller效应，预计是重要的两个属性，但实际的耦合强度是迄今为止未知的。基于密度泛函计算，我们确定了C60分子的两个ag、6 gg和8 hg振动模与Hu最高占据轨道能级的线性耦合.耦合预测的D5失真，和胡振子基态C60+。它们还用于产生无量纲耦合常数λ，该常数控制超导性和声子对晶相电阻率的贡献。我们发现，在带正电的C60比在负掺杂的情况下，λ大1.4倍。这些结果进行了讨论的背景下，现有的运输数据和超导温度。更高的轨道简并度在超导性中的作用也得到了解决。
Abstract Recent experiments have shown that C60 can be positively field doped. In that state, fullerene exhibits a higher resistivity and a higher superconducting temperature than the corresponding negatively doped state. A strong intramolecular hole–phonon coupling, connected with the Jahn–Teller effect of the isolated positive ion, is expected to be important for both properties, but the actual coupling strengths are so far unknown. Based on density functional calculations, we determine the linear couplings of the two ag six gg and eight hg vibrational modes to the Hu highest occupied molecular orbital level of the C60 molecule. The couplings predict a D5 distortion, and an Hu vibronic ground state for C60 +. They are also used to generate the dimensionless coupling constant λ which controls the superconductivity and the phonon contribution to the electrical resistivity in the crystalline phase. We find that λ is 1.4 times larger in positively charged C60 than in the negatively doped case. These results are discussed in the context of the available transport data and superconducting temperatures. The role of higher orbital degeneracy in superconductivity is also addressed.