Dielectric Response of Organic Charge-Transfer (ct) Salts with Neutral-Ionic and Peierls Transitions.
Abstract
The dipole operator P(F) of systems with periodic boundary conditions in a static electric field F is applied to one-dimensional Peierls-Hubbard models of CT salts. Exact equilibrium results for chains with N = 14 and 16 sites yield converged results for the polarizability, dP/dF, both electronic and vibrational. Typical parameters for CT salts lead to huge dielectric constants (κ ∼ 100-1000) near the Peierls instability, where κ is dominated by charge fluctuations driven by lattice phonons. We model dielectric anomalies in 1:1 salts of dimethyltetrathiafulvalene (DMTTF) and substituted chloranils (CA), and show that soft lattices have continuous (second-order) Peierls transitions at low ionicity in contrast to the familiar discontinuous (first-order) transition in TTF-CA.
- Publication:
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APS March Meeting Abstracts
- Pub Date:
- March 2004
- Bibcode:
- 2004APS..MARV19004S