A quantum-mechanical model of quasi-one-dimensional conductors

We present a model of a quasi-one-dimensional (Q1D) conductor with weak dis persion in the direction perpendicular to the chains in a magnetic field. F inite-energy electric dipole transitions between the eigenstates of the sys tem constitute Fermi-surface traversal resonance, a Q1D analogue of cyclotr on resonance. We extend the model to describe a (TMTSF)(2)X-like material, with dispersion in two directions perpendicular to the chains, and find tha t for certain orientations of the magnetic field large degeneracies occur b etween the magnetic-field induced states. These are angles at which maxima are observed experimentally in the d.c. conductivity, and thus we explain o ne class of angle-dependent magnetoresistance oscillations (AMRO) in terms of zero-energy electric dipole transitions between magnetic-field induced s tates.