Abstract
The success of Hubbard model in describing the correlation effects in d electrons of the transition metals has attracted a lot of interest between physicists. the special importance of this model is that it describes the metal-insulator Mott transition and also high Tc superconductors.
In this work, we introduce this model, and investigate the Hubbard hamiltonian.
There are quite a few approximate solution for this hamiltonain, which we have introduced some of them, and considered the conditions for the the existence of ferromagnetism in these solutions.
There are a few exact solution for Hubbard model, only in special cases. Here we have studied the exact solution in one dimension.