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Eletronic and phonomic states of the Holstein-Hubbard dimer of variable length

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Eletronic and phonomic states of the Holstein-Hubbard dimer of variable length

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Título Eletronic and phonomic states of the Holstein-Hubbard dimer of variable length
Autor Acquarone, C.
Iglesias, Jose Roberto
Gusmao, Miguel Angelo Cavalheiro
Noce, A.
Romano, Alfonso
Abstract We consider a model Hamiltonian for a dimer of length a including all the electronic one- and two-body terms consistent with a single orbital per site, a free Einstein phonon term for a frequency V, and an electronphonon coupling g0 of the Holstein type. The bare electronic interaction parameters were evaluated in terms of Wannier functions built from Gaussian atomic orbitals. An effective polaronic Hamiltonian was obtained by an unrestricted displaced-oscillator transformation, followed by evaluation of the phononic terms over a squeezedphonon variational wave function. For the cases of quarter-filled and half-filled orbitals, and over a range of dimer length values, the ground state for given g0 and Ω was identified by simultaneously and independently optimizing the orbital shape, the phonon displacement, and the squeezing effect strength. As a varies, we generally find discontinuous changes of both electronic and phononic states, accompanied by an appreciable renormalization of the effective electronic interactions across the transitions, due to the equilibrium shape of the wave functions strongly depending on the phononic regime and on the type of ground state.
Contido em Physical review. B, Condensed matter and materials physics. Woodbury. Vol. 58, no. 12 (Sept. 1998), p. 7626-7636
Assunto Fisica teorica da materia condensada
Interacao electron-fonon
Modelo de hubbard
Sistemas hamiltonianos
Origem Estrangeiro
Tipo Artigo de periódico
URI http://hdl.handle.net/10183/104004
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