1Department of Physics, Peking University, Beijing 100871
2Institute of Theoretical Physics, Chinese Academy of Sciences, PO Box 2735, Beijing 100080
3PHP Institute for Bioengineering and Bioscience, Georgia Institute of Technology, 315 First Drive, Atlanta, GA 30332-0363, USA
4Interdisciplinary Center of Theoretical Studies, Chinese Academy of Sciences, PO Box 2735, Beijing 100080
Exciton Excitations in a One-Dimensional Band Insulator with Hubbard Interactions
1Department of Physics, Peking University, Beijing 100871
2Institute of Theoretical Physics, Chinese Academy of Sciences, PO Box 2735, Beijing 100080
3PHP Institute for Bioengineering and Bioscience, Georgia Institute of Technology, 315 First Drive, Atlanta, GA 30332-0363, USA
4Interdisciplinary Center of Theoretical Studies, Chinese Academy of Sciences, PO Box 2735, Beijing 100080
Abstract： We study the properties of exciton excitations in the Hubbard model with alternating potential and dimerized hopping terms at half-filling. With increasing Coulomb repulsion, we find that a spin triplet exciton band develops below the band gap. At certain critical interaction, the excitation gap of this exciton band vanishes and a new phase with a dimerized ground state emerges. The value of this critical Coulomb interaction is determined perturbatively.
2004, Vol. 21 
