Correlation Effect on Optical Absorption in One-Dimensional Peierls-Hubbard Systems

概要

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Effects of the electron correlation on the optical absorption due to inter-band transition (CT absorption) and due to non-linear excitations (mid-gap absorption) in one-dimensional Peierls-Hubbard CDW systems are studied by using the exact diagonalization method. The correlation effect of on-site repulsion U is fairly small for both the CT and the mid-gap absorption except in the boundary region between the CDW and AF phases while the correlation effect of inter-site repulsion V is significant for both the transitions. With increasing V the CT transition is suppressed and the exciton transition grows. As to the mid-gap absorption the intensities of absorption associated with the transitions from (or to) a defect state of the non-linear excitations to (or from) a conduction- or valence-band state are enhanced strongly by the effect of V. The absorption spectrum in the AF state is also calculated. Only the lowest optically-allowed state has a large oscillator strength and hence the absorption spectrum in the AF state is very sharp compared with the CT transition in the CDW state.
社団法人日本物理学会の論文
1995-05-15