2kFPeierls Transition for a Half-Filled Band from a Hubbard Hamiltonian Extended with Intersite-Dependent Transfer

Abstract
We report a model calculation with the Hubbard Hamiltonian, extended with an exponentially dependent intersite transfer, on a half-filled band system. The calculation shows a phase transition which changes from an electronic (at low U/t) to a spin Peierls at high U/t. In the presence of an extemal magnetic field a new phase (2kF + kF ) was found. The specific heat, spin susceptibility, and intensity of the charge transfer absorption was calculated; the results compare reasonably well with experiment. In addition the pressure dependence of the phase transition temperature could be estimated.