I am currently writing a code for the Bose-Hubbard model, and I am calculating the ground states and single-particle density matrix for different values of U and J. As U=0, one would see how the energy gap between the first two energy states would close, which happens. However, as I look at the eigenvector of the ground energy -describing my ground state- I can see that it is changing for every run.

I suspect this is happening due to the ground state being degenerate (the gap has closed) but then how would I compute a valid eigenvector? Is there a method correcting the scipy.sparse.linalg.eigsh for these cases?

  • $\begingroup$ Please clarify your specific problem or provide additional details to highlight exactly what you need. As it's currently written, it's hard to tell exactly what you're asking. $\endgroup$
    – Community Bot
    Feb 3 at 4:40


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