Gutzwiller wave function under magnetic field

Robert Joynt, Claudius Gros, Thomas Maurice Rice

Hisatoshi Yokoyma, Shinya Tokizaki

Magnetization process of the Gutzwiller wave function is studied accurately by a variational Monte Carlo method. We apply it to the one-dimensional (1D) and 2D Hubbard models (HM), and to the 1D periodic Anderson model (PAM) without orbital degeneracy. For the HM, magnetization varies discontinuously to the full moment, as the magnetic field increases. For the PAM, the paramagnetic state is unstable against ferromagnetism, although the energy reduction thereof is small.

Florian Gebhard, Martin C. Gutzwiller

K. Hallberg, Alberto G. Rojo, C. A. Balseiro

We study the Gutzwiller ansatz with a gauge field and aribtrary polarization as a trial wave function for the spin-liquid state of the Heisenberg Hamiltonian in two dimensions. This wave function is evaluated exactly for a 4\ifmmode\times\else\texttimes\fi{}4 cluster with periodic boundary conditions. The energy as a function of the gauge field and magnetization is calculated.

Michele Fabrizio

We introduce an extension of the Gutzwiller variational wave function able to deal with insulators that escape any mean-field-like description, as, for instance, nonmagnetic insulators. As an application, we study the Mott transition from a paramagnetic metal into a nonmagnetic Peierls, or valence-bond, Mott insulator. We analyze this model by means of our Gutzwiller wave function analytically in the limit of large coordination lattices, where we find that (1) the Mott transition is of first order; (2) the Peierls gap is large in the Mott insulator, although it is mainly contributed by the electron repulsion; and (3) singlet superconductivity arises around the transition.

B. Sriram Shastry, T. V. Ramakrishnan