Variational Solutions of the Hubbard Model for the bcc Lattice

Abstract

A variational method is used to find approximative solutions of the Hubbard model for the ground state of the bcc lattice in the weak and strong coupling limits. The neutral case (a half-filled band) is found to be antiferromagnetic for all values of the coupling constant. However, for other choices of the band· filling second phase transitions between different magnetic structures are found if the coupling constant is varied.