engleski

Quantum transport equations for low-dimensional multiband electronic systems. I

A systematic method of calculating the dynamical conductivity tensor in a general multiband electronic model with strong boson-mediated electron-electron interactions is described. The theory is based on the exact semiclassical expression for the coupling between valence electrons and electromagnetic fields and on the self-consistent Bethe-Salpeter equations for the electron-hole propagators. The general diagrammatic perturbation expressions for the intraband and interband single-particle conductivity are determined. The relations between the intraband Bethe-Salpeter equation, the quantum transport equation and the ordinary transport equation are briefly discussed within the memory-function approximation. The effects of the Lorentz dipole-dipole interactions on the dynamical conductivity of low-dimensional sp_alpha models are described in the same approximation. Such formalism proves useful in studies of different (pseudo)gapped states of Q1D systems with the metal-to-insulator phase transitions and can be easily extended to underdoped 2D high-T_c superconductors.

optical conductivity; quantum transport equations; Bethe--Salpeter equations

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