BAND TO CORRELATED CROSSOVER IN ALTERNATING HUBBARD AND PARISER-PARR-POPLE CHAINS - NATURE OF THE LOWEST SINGLET EXCITATION OF CONJUGATED POLYMERS

被引:124
作者
SOOS, ZG
RAMASESHA, S
GALVAO, DS
机构
[1] INDIAN INST SCI,SOLID STATE & STRUCT CHEM UNIT,BANGALORE 560012,KARNATAKA,INDIA
[2] BELL COMMUN RES INC,RED BANK,NJ 07701
[3] UNIV ESTADUAL CAMPINAS,DEPT FIS APLICADA,BR-13081 CAMPINAS,SP,BRAZIL
关键词
D O I
10.1103/PhysRevLett.71.1609
中图分类号
O4 [物理学];
学科分类号
0702 ;
摘要
The evolution with increasing Coulomb correlations of a semiconductor to a magnetic insulator is related to an excited-state crossover in pi-electron models for conjugated polymers. We associate strong fluorescence with a lowest singlet excitation S1 that is dipole allowed, on the band side, while S1 becomes two-photon allowed on the correlated side. S1/S2 crossovers in Hubbard, Pariser-Parr-Pople, or other chains with electron-hole symmetry and alternating transfer integral t(1 +/- delta) are based on exact results at delta=0 and 1, on molecular exciton theory at large delta, and on oligomer calculations up to twelve sites.
引用
收藏
页码:1609 / 1612
页数:4
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