Study of strongly correlated electron systems by the dynamical mean field theory

Abstract

The dependence of the spectral function near the CT (Charge Transfer)-type metal-insulator transition point on the electron number was studied. It was found that the lowest excitation in the insulating state is the local singlet state formed by a d-hole and a p-hole. The same model was studied also by exact diagonalization of small clusters. The result confirmed the conclusion obtained above. Next, the two-band model (the periodic Anderson model) was studied where repulsive interaction works not only between localized electrons but also between conduction electrons. As the results contradicted to the result obtained by the Gutzwiller variation method. The reason for the discrepancy is now investigating. Electronic states in asymmetric double-layer electron system under a strong magnetic field were also investigated. It was found that the ground state is well approximated, at certain conditions, by the generalized Laughlin wave function.

電荷移動型金属-絶縁体転移点近傍でのスペクトル関数の電子数依存性を研究した。絶縁体状態の最低励起は、d正孔とp正孔による局所1重項であることが分かった。同じ模型を小クラスタの厳密対角化で研究した。その結果は、上記の結論を確認するものであった。次に、反発相互作用が局在電子間だけでなく伝導電子間にも働く2バンド模型(周期アンダーソン模型)を研究した。その結果がGutzwiller変分法で得られた結果と矛盾するので、その理由を追究している。また、強磁場での非対称2重層電子系の電子状態を研究した。基底状態は、ある条件下では、一般化Laughlin波動関数で良く近似できることが分かった。