Recent content by Gec

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    Graduate Is the Ground State Energy of the Two-Dimensional XX Model Known?

    to yuanyuan5220, thanks for your message. Really, Jordan-Wigner transformation in one-dimensional case reduces the XX model to free fermions model, which is exactly solvable. In two dimensions it doesn't work. Can you explain to me what is "old archives in prl and prb at 1980s", please?
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    Graduate Is the Ground State Energy of the Two-Dimensional XX Model Known?

    I am curious about XX model with quantum 1/2-spins in two dimensions. Is ground state energy for this model known? I was not able to find numerical or theoretical results in electronical archives.
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    Graduate A question about the ground state wave function of XXZ model

    1D XY model with external field is equivalent to free fermions model. Because of this the ground state wave function has simple form. XXZ model can't be reduced to free fermions. Eigenfunctions of XXZ model have the form of Bethe ansatz. If external field is present, it is unknown what function...