title: Spontaneous deformation of the fermi surface due to strong correlation in the two-dimensional t- J model
abstract: The Fermi surface of the two-dimensional t- J model is studied using the variational Monte Carlo method. We study the Gutzwiller-projected d-wave superconducting state with an additional variational parameter t(')(v) corresponding to the next-nearest-neighbor hopping term. It is found that the finite t(')(v)<0 gives the lowest variational energy in the wide range of hole-doping rates. The obtained momentum distribution function shows that the Fermi surface deforms spontaneously. It is also shown that the Van Hove singularity is always located very close to the Fermi energy. Using the Gutzwiller approximation, we show that this deformation is due to the Gutzwiller projection operator or the strong correlation.
authors.affiliation: Department of Basic Science, Graduate School of Arts and Sciences, University of Tokyo, Komaba, Meguro-ku, Tokyo 153-8902, Japan.
authors.initials: A
authors.lastname: Himeda
authors.initials: M
authors.lastname: Ogata