ITINERANT VIBRONIC POLARONS: A MERRIFIELD APPROACH. LOW ENERGY RANGE CALCULATIONS

We extend Merrifield's Variational Ansatz in the variational band theory of polarons to cover a frame of two electronic bands mixed by an Ein- stein phonon. The Hamiltonian is composed of the local and hopping energy terms, the vibrational energy, and a band-mixing term linear in the electron- phonon coupling. The eigenstate is a linear combination of Merrifield states for either electron band. The variational equations are solved numerically, so as to obtain the energy vs. momentum relation in ground state. Our vari- ational method generates either Jahn-Teller polarons if the electronic bands degenerate or pseudo-Jahn-Teller polarons if they nearly degenerate, both en- tities regarded as likely carriers in metal-oxygen manifolds of high-Tc super- conducting cuprates and colossal magnetoresistance exhibiting manganates.