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Phys. Rev. B 64, 121105(R) (2001) [4 pages]

Phase diagram of the Hubbard chain with two atoms per cell

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M. E. Torio1, A. A. Aligia2, and H. A. Ceccatto1
1Instituto de Física Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas and Universidad Nacional de Rosario, Boulevard 27 de Febrero 210 bis, (2000) Rosario, Argentina
2Centro Atómico Bariloche and Instituto Balseiro, Comisión Nacional de Energía Atómica, 8400 Bariloche, Argentina

Received 30 April 2001; published 11 September 2001

We obtain the quantum phase diagram of the Hubbard chain with alternating on-site energy at half filling. The model is relevant for the ferroelectric perovskites and organic mixed-stack donor-acceptor crystals. For any values of the parameters, the band insulator is separated from the Mott insulator by a dimer phase. The boundaries are determined accurately by crossing of excited levels with particular discrete symmetries. We show that these crossings coincide with jumps of charge and spin Berry phases with a clear geometrical meaning.

© 2001 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevB.64.121105
DOI:
10.1103/PhysRevB.64.121105
PACS:
71.30.+h, 71.10.Hf, 71.10.Pm, 77.80.-e
 
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