Exact non-adiabatic solutions of the peierls-hubbard hamiltonian

Michael Schreiber, W. Schmidt

Sigrid M. Weber, H. Büttner

Garcia Saravia Ortiz de Montellano Andres, J. Mustre de León

David K Campbell, J. Tinka Gammel, Eugene Loh

Miguel Cárdenas, David Gottlieb, Jaime Rössler

The exact solution of the Hubbard-Peierls model is given in a cluster of six atoms and three spinless electrons. Phonons with wave vector k=\ensuremath{\pi} are retained and quantum mechanically analyzed. Energy level and several averages are evaluated, thus determining the physical properties of the model in terms of the parameters of the system. The regime of the distorted lattice is obtained. The exact and Born-Oppenheimer (BO) results are compared, concluding that the BO enhances quantum fluctuations; this peculiar behavior is explained.

Michael Dzierzawa, Carmen Luminiţa Mocanu

We investigate the Peierls transition in the one-dimensional Peierls-Hubbard model at half filling in the adiabatic approximation for the lattice. Depending on the value of the electron-lattice coupling constant g the equilibrium dimerization can be either enhanced or suppressed by the Hubbard interaction U. Applying second order perturbation theory we determine the critical value g_c = 0.689348 below which the Hubbard interaction enhances the dimerization.