Nonadiabatic theory of electron–vibrational coupling: New basis for microscopic interpretation of superconductivity

Abstract

AbstractThe electron–vibrational problem of the general nonadiabatic molecular systems has been solved by means of the quasi‐particle transformations. The SCF ab initio solution of the nonadiabatic fermion Hamiltonian yields stabilization of the electronic ground‐state energy due to electron–phonon interaction and it also gives the corrections to the one‐ and two‐particle terms. Two two‐particle correction yields effective attractive electron–electron interaction, but in the form different from Frölich's effective electron–electron interaction term. In contrast to the standard electron–phonon Hamiltonian of solid‐state physics that does not take into account the possible effects of nonadiabaticity of a system, the presented nonadiabatic theory yields also one‐particle corrections. The presence of this term in the Hamiltonian might play a crucial role in the theory of superconductivity since the superconductors are nonadiabatic systems.