高温有机超导的可能性

本文讨论了高温有机超导所遇到的两个主要问题。首先,从描写有机分子电子态的Bloch波函数出发,利用微扰论,证明了有机分子中的Coulomb场由于可移动电子的存在仍然将产生某种屏蔽作用,其屏蔽长度的平方与Fermi能级处的态密度成反比。其次,利用包含σ键压缩能的分子轨道理论,得到了象聚二苯(polyacenacene)这类有机分子有可能不发生Peierls畸变。由此表明,在其他条件满足时,在某些有机分子中出现超导态是完全可能的,同时也指出了有机材料在Fermi能级处具有较大的态密度似乎是实现Little有机超导设想的关键。

THE POSSIBILITY OF THE EXISTENCE OF ORGANIC SUPERCONDUCTIVITY

In this article, we discuss two important problems about possible superconductivity in organic molecules. One problem concerns the instability of an one-dimensional metal (Peierls distortion). The other is associated with screening of the Coulomb interaction between electrons in organic molecules. First, using Bloch function to describe electronic states, we have shown that some screening of the Coulomb field in organic molecules must occur. The square of screening length is inversely proportional to the density of states at the Fermi level. Next, we have found that for polyacenacene the regular structure is stable with respect to the Peierls distortion, and that bond alternation does not happen. Moreover, polyacenacene has large density of states at the Fermi level, which makes the effective interaction attractive, and the presence of polarizable substituents superconductivity will be possible if other requirements are met.