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Exact Ground State of the 2D Hubbard Model at Half Filling for $U=0^{+}$

Michele Cini·Gianluca Stefanucci
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Abstract

We solve analytically the $N\times N$ square lattice Hubbard model for even $N$ at half filling and weak coupling by a new approach. The exact ground state wave function provides an intriguing and appealing picture of the antiferromagnetic order. Like at strong coupling, the ground state has total momentum $K_{tot}=(0,0)$ and transforms as an $s$ wave for even $N/2$ and as a $d$ wave otherwise.

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Michele Cini, Gianluca Stefanucci. 2000-07-07. Exact Ground State of the 2D Hubbard Model at Half Filling for $U=0^{+}$. https://doi.org/10.1016/s0038-1098(00)00504-4

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