Relationship between incommensurability and superconductivity in Peierls-distorted charge-density-wave systems

We study the pairing potential induced by fluctuations around a charge-dens ity wave (CDW) with scattering vector Q by means of the Frohlich transforma tion. For general commensurability M, defined as \ k+MQ) =\ k), we iind tha t the intraband pair scattering within the M subbands scales with M, wherea s the interband pair scattering becomes suppressed with increasing CDW orde r parameter. As a consequence superconductivity is suppressed when the Ferm i energy is located between the subbands as it is usually the case for nest ing induced CDW's, but due to the vertex renormalization it can be substant ially enhanced when the chemical potential is shifted sufficiently inside o ne of the subbands. The model can help to understand the experimentally obs erved dependence of the superconducting transition temperature from the str ipe phase incommensurability in the lanthanum cuprates. [S0163-1819(99)0294 2-2].