2k_F Peierls 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 (2k_F + k_F ) 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.