Volume 83, Number 3, August 2008
Article Number 37001
Number of page(s) 5
Section Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties
Published online 30 June 2008
EPL, 83 (2008) 37001
DOI: 10.1209/0295-5075/83/37001

Dimerization transition of alkali-TCNQ salts: Charge degrees of freedom near the CDW boundary

Manoranjan 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 $\delta $. Charge-transfer absorption and $\delta (V)$ 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.

© EPLA 2008