AbstractIn this paper we study the excitation spectrum of the organic conductor tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ) using finite temperature calculations. The effect of electronelectron interaction is considered within the random phase approximation (RPA). Our results show the temperature dependent plasmon and dipolar mode corresponding qualitatively to the modes obtained previously using zero temperature formalism assigned to the observed excitations at 10 meV and 0.75 eV. These modes have an essential influence on the energy-loss function. The obtained results are in good qualitative agreement with the optical and EELS data of TTF-TCNQ.
It has been shown that in light scattering experiments with polymers replacement of a solvent by a solvent mixture causes problems due to preferential adsorption of one of the solvents. The present paper extends this theory to be applicable to any angle of observation and any concentration by using the random phase approximation theory proposed by de Gennes. The corresponding formulas provide expressions for molecular weight, gyration radius, and the second virial coefficient, which enables measurements of these quantities provided enough information on molecular and thermodynamic quantities is available.
Theory of the magnetization and exchange-enhanced susceptibility of alloys. I. Zero-temperature susceptibility of paramagnetic alloys in the random-phase approximation
