We study electron-electron pairing in an one-dimensional model lattice system embedded into a three-dimensional environment. The electron pair potential is lowered by a single, localized lattice deformation. Such a deformation is related to solitons moving along the lattice. Yet the exact form and the time evolution of the lattice excitation are of secondary relevance as the electron pair is st...

A new mechanism for the formation of doped polyaniline is presented. Besides providing suitable structural and spectroscopic parameters, the new mechanism allows for the rationalization of the experimentally observed equilibrium between polaron and bipolaron defects in emeraldine salt. The magnetic behavior and the "metallic island" model for conduction in doped polyaniline are also theoretical...

Combining density-matrix and Lanczos algorithms we propose a new optimized phonon approach for finite-cluster diagonalizations of interacting electronphonon systems. To illustrate the efficiency and reliability of our method, we investigate the problem of bipolaron band formation in the extended Holstein Hubbard model.

We provide a unified parameter-free explanation of the observed oxygen-isotope effects on the critical temperature, the magnetic-field penetration depth and on the normal-state pseudogap for underdoped cuprate superconductors within the framework of the multi-(bi)polaron theory with strong Coulomb and Fröhlich interactions. We also quantitatively explain the measured critical temperature and th...