Croatica Chemica Acta, Vol. 86 No. 4, 2013.
Original scientific paper
https://doi.org/10.5562/cca2324
Quantum Phase Diagram of One-Dimensional Spin and Hubbard Models with Transitions to Bond Order Wave Phases
Manoranjan Kumar
; S. N. Bose National Centre for Basic Sciences, Block-JD, Sector-III, Salt Lake, Kolkata-700098, India
S. Ramasesha
; Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India
Zoltán G. Soos
; Department of Chemistry, Princeton University, Princeton NJ 08544, USA
Abstract
Similar quantum phase diagrams and transitions are found for three classes of one-dimensional
models with equally spaced sites, singlet ground states (GS), inversion symmetry at sites and a bond order
wave (BOW) phase in some sectors. The models are frustrated spin−1/2 chains with variable range
exchange, half-filled Hubbard models with spin-independent interactions and modified Hubbard models
with site energies for describing organic charge transfer salts. In some range of parameters, the models
have a first order quantum transition at which the GS expectation value of the sublattice spin SA
2 of odd
or even-numbered sites is discontinuous. There is an intermediate BOW phase for other model parameters
that lead to two continuous quantum transitions with continuous SA
2. Exact diagonalization of finite
systems and symmetry arguments provide a unified picture of familiar 1D models that have appeared
separately in widely different contexts. (doi: 10.5562/cca2324)
Keywords
bond order wave phases; quantum phase transitions; frustrated spin chains; extended Hubbard models; neutral-ionic transition models
Hrčak ID:
112763
URI
Publication date:
16.12.2013.
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