Actually both the “abs” and “^” operators seem to be allowed, but the problem might come from the (i-j) term.

Using the coordinates in the coefficients is instead a non-trivial feature. It only works if you define the lattice as inhomogeneous. You should see some examples non the lattices.xml file.

As an alternative solution, you could define the lattice as a graph and set independent coefficients on the bonds and edges. You should find other examples in the mailing list, or on this page https://alps.comp-phys.org/mediawiki/index.php/Tutorials:LatticeHOWTO:SimpleGraphs

Best,

Michele

On 27 Jun 2017, at 08:14, John Ian Kenneth E. Felismino <jfelismino@nip.upd.edu.ph> wrote:

Hi!

The hamiltonian I'm using is attached as a picture file. As you can see, the bond terms are proportional to abs(i - j)^\alpha. i was wondering if this is possible in Alps because I have tried doing it (crudely) with DMRG and found that it did not produce an output xml. I had simply added the term "/abs(i-j)^alpha#" in my hamiltonian.  When I remove this term, the Hamiltonian works, so clearly the problem is with this proportionality term.

Thanks.

Ian Felismino

<Kitaev Hamiltonian.png>

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