Fabio Mezzacapo, Massimo Boninsegni
We study the ground-state phase diagram of the quantum $J_1-J_2$ model on the
honeycomb lattice by means of an entangled-plaquette variational ansatz. Values
of energy and relevant order parameters are computed in the range $0\le
{J_2}/{J_1} \le 1$. The system displays classical order for
${J_2}/{J_1}\lesssim 0.2$ (N\'eel), and for $J_2/J_1 \gtrsim 0.4$ (collinear).
In the intermediate region, the ground-state is disordered. Our results show
that the reduction of the half-filled Hubbard model to the model studied here
does not yield accurate predictions.
View original:
http://arxiv.org/abs/1109.3681
No comments:
Post a Comment