engleski

Multiband model for organic chain conductors

The molecules in organic chain conductors are usually highly polarizable. In order to include the corresponding intramolecular contributions into the modeling of these materials with typical Pi intermolecular bonding, we use our recently developed tight binding formalism for the dielectric matrix of multiband systems. By this approach we take into account all long-range and short-range Coulomb interactions, and are able to calculate straightforwardly, at the random phase approximation level, frequencies of collective modes, correlation contributions to the cohesive energy, etc. The application of the above formalism to the acceptor-donor salts like TTFTCNQ leads to the explanation of their well-known cohesive properties, like the fractional charge transfer, the formation of charged sheets in the crystal structures, and the so-called Madelung defect which appears in the standard ionic cohesive scheme. The same calculations enable also the interpretation of unusual low frequency excitations observed in the infrared measurements.

organic conductors; collective modes; cohesive energy

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