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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

Puni tekst: engleski pdf 1.949 Kb

str. 407-417

preuzimanja: 1.362



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)

Ključne riječi

bond order wave phases, quantum phase transitions, frustrated spin chains, extended Hubbard models, neutral-ionic transition models

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