This study of the one-dimensional ~1D! Su-Schrieffer-Heeger model in a weak-coupling perturbative regime points out the effective-mass behavior as a function of the adiabatic parameter vp /J, where vp is the zoneboundary phonon energy and J is the electron band hopping integral. Computation of low order diagrams shows that two-phonon scattering processes become appreciable in the intermediate regime in which zoneboundary phonons energetically compete with band electrons. Consistently, in the intermediate ~and also moderately antiadiabatic! range the relevant mass renormalization signals the onset of a polaronic crossover whereas the electrons are essentially undressed in the fully adiabatic and antiadiabatic systems. The effective mass is roughly twice as much the bare band value in the intermediate regime while an abrupt increase ~mainly related to the peculiar 1D dispersion relations! is obtained at vp;A2J.
Mass renormalization in the Su-Schrieffer-Heeger model
ZOLI, Marco
2002-01-01
Abstract
This study of the one-dimensional ~1D! Su-Schrieffer-Heeger model in a weak-coupling perturbative regime points out the effective-mass behavior as a function of the adiabatic parameter vp /J, where vp is the zoneboundary phonon energy and J is the electron band hopping integral. Computation of low order diagrams shows that two-phonon scattering processes become appreciable in the intermediate regime in which zoneboundary phonons energetically compete with band electrons. Consistently, in the intermediate ~and also moderately antiadiabatic! range the relevant mass renormalization signals the onset of a polaronic crossover whereas the electrons are essentially undressed in the fully adiabatic and antiadiabatic systems. The effective mass is roughly twice as much the bare band value in the intermediate regime while an abrupt increase ~mainly related to the peculiar 1D dispersion relations! is obtained at vp;A2J.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
