Dimerization transition of alkali-TCNQ salts: Charge degrees of freedom near the CDW boundaryManoranjan Kumar1, S. Ramasesha1, R. A. Pascal jr.2 and Z. G. Soos2
1 Solid State and Structural Chemistry Unit, Indian Institute of Science - Bangalore 560012, India
2 Department of Chemistry, Princeton University - Princeton, NJ 08544, USA
received 22 May 2008; accepted in final form 16 June 2008; published August 2008
published online 30 June 2008
Stacks of TCNQ- radical ions in 1 : 1 alkali salts are shown to be near the charge-density-wave (CDW) boundary, where charge degrees of freedom induce strong dimerization . Charge-transfer absorption and are obtained for a one-dimensional (1D) Hubbard model with long-range Coulomb interactions V that ranges from spin-Peierls at V=0 to the CDW boundary at Vc and beyond. Cation dimerization lifts the degeneracy of Peierls systems and confers 3D contributions to the dimerization transition of alkali-TCNQ salts.
71.10.Fd - Lattice fermion models (Hubbard model, etc.).
71.30.+h - Metal-insulator transitions and other electronic transitions.
71.45.Lr - Charge-density-wave systems.
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