Anomalous Nature of Neutral-to-Ionic Phase Transition in Tetrathiafulvalene-Chloranil

Quantum Monte Carlo methods are used to study a quantum phase transition in a 1D Hubbard model with a staggered ionic potential (∆). Using recently formulated methods, the electronic polarization and localization are determined directly from the correlated ground state wavefunction and compared to results of previous work using exact diagonalization and Hartree-Fock. We find that the model undergoes a thermodynamic transition from a band insulator (BI) to a broken-symmetry bond ordered (BO) phase as the ratio of U/∆ is increased. Since it is known that at ∆ = 0 the usual Hubbard model is a Mott insulator (MI) with no long-range order, we have searched for a second transition to this state by (i) increasing U at fixed ∆ and (ii) decreasing ∆ at fixed U. We find no transition from the BO to MI state, and we propose that the MI state in 1D is unstable to bond ordering under the addition of any finite ionic potential ∆. In real 1D systems the symmetric MI phase is never stable and the transition is from a symmetric BI phase to a dimerized BO phase, with a metallic point at the transition.

show abstract

“…This is experimentally confirmed by Torrance et al 56 ; where upon increasing the electronic interaction a BI → BO transition takes place.…”

supporting

confidence: 73%

Quantum Monte Carlo study of the one-dimensional ionic Hubbard model

2001

View full text Add to dashboard Cite

show abstract

“…22 An expanded energy scale is needed to show E  (g) in this range, and it is plausible to anticipate that the infinite chain has doubly degenerate GS with broken inversion symmetry over an interval in g. The  = ±1 GS at g 10 are well approximated 22 by the product GG of sublattices in their singlet GS and the singlet linear combination 1 TT of sublattices in the lowest triplet state. Moreover, the magnetic gap E m (g) in Figure 2 exceeds finitesize effects in the interval g MG < g < g 10 . The J 1 J 2 model has a BOW phase with broken  symmetry and finite E m .…”

Section: Frustrated Spin−1/2 Chainsmentioning

confidence: 99%

“…Six arrows from g MG =1 / 2 to g 10 indicate degenerate GS where E  (g) = 0. The notation g 10 is related to the analytical model summarized in the Appendix, whose GS in the sectors S A = S B = 1 and 0 are degenerate at g 10 . Since ED respects all symmetries, eigenstates are even or odd under inversion.…”

Section: Frustrated Spin−1/2 Chainsmentioning

confidence: 99%

“…The third class is E 0 (, V) in the restricted basis 9 of modified Hubbard models with site energy ±, transfer integral t = 1 and electrostatic (Madelung) energy E M =  M V for Coulomb interaction V between neighbors. The model has been applied to neutral-ionic transitions 10 (NIT) in organic charge transfer (CT) salts 11−13 that contain mixed 1D stacks of planar -electron donors (D) and acceptors (A). The neutral and ionic limits sketched in Figure 1b have two electrons in the HOMO of D and one electron transferred to the LUMO of A, respectively.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Quantum Phase Diagram of One-Dimensional Spin and Hubbard Models with Transitions to Bond Order Wave Phases

2013

View full text Add to dashboard Cite

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 S

show abstract

“…Charge transfer complexes have unique absorption bands in the ultraviolet-visible region. Some of the charge transfer complexes containing chloranil as an acceptor have been reported [3][4][5][6][7][8][9][10] .…”

Section: Introductionmentioning

confidence: 99%

Spectroscopic Studies on Charge Transfer Complexes of Chloranil with Novel 6-(Trifluoromethyl)furo[2, 3-b] pyridine-2-carbohydrazide Derivatives

2014

Chem Sci Trans

View full text Add to dashboard Cite

A sensitive spectrophotometric method was employed to study the charge transfer complex of chloranil with 6-(trifluoromethyl)furo [2, 3-b]pyridine-2-carbohydrazide derivatives (TFC). The method is based on the reaction of these drugs as n-electron donors with the pi-acceptor 2,3,5,6-tetrachloro-1,4-benzoquinone. The obtained coloured charge transfer complex was measured at 412 nm by UV-Vis spectrophotometer. The obtained complexes were confirmed by 1 H NMR and IR spectral analysis. The proposed procedure could be applied successfully to the determination of the association constants and standard free energy changes using Benesi-Hildebrand plots.

show abstract

Anomalous Nature of Neutral-to-Ionic Phase Transition in Tetrathiafulvalene-Chloranil

Cited by 411 publications

References 9 publications

Quantum Monte Carlo study of the one-dimensional ionic Hubbard model

Quantum Monte Carlo study of the one-dimensional ionic Hubbard model

Quantum Phase Diagram of One-Dimensional Spin and Hubbard Models with Transitions to Bond Order Wave Phases

Spectroscopic Studies on Charge Transfer Complexes of Chloranil with Novel 6-(Trifluoromethyl)furo[2, 3-b] pyridine-2-carbohydrazide Derivatives

Contact Info

Product

Resources

About