Deformation of fermi surface due to many-body effect: renormalization group approach

Perturbational renormalization group (RG) is used to study the renormalization of the Fermi surface (FS) of the t-t' Hubbard model. We construct and solve numerically the RG equations for t, t' and U, and found that FS is deformed towards nesting at half-filling. Phase boundary of the antiferromagnetic state and the paramagnetic state in U/t-t'/t plane is determined exactly in the weak coupling region. (C) 2002 Elsevier Science B.V. All rights reserved.