The effect of intra-molecular vibrations on the transition temperature of high Tc superconductors

Abstract A mean field calculation is made for a Peierls-Hubbard Hamiltonian supplemented by a term describing electron coupling to intra-molecular vibrations. This has the effect of renormalising the parameters t and U in the Hubbard model in such a way as to decrease the transition temperature T c . Thus the coupling between electrons and intra-molecular vibration puts a restriction on T c . It is pruposed that the Hubbard model of electrons must be coupled to both the inter- and intra-molecular vibrations to provide a complete description of the essential features of the high T c oxide superconductors.