[ALPS-users] Interaction involving three lattice sites

Dear ALPS community,

I was wondering if it is possible to define an interaction involving three different lattice sites (for a 1D lattice model to perform dmrg calculations). To clarify, an example would be to construct the term \sum_i n_i n_{i+1} n_{i-1}. I checked in the doc if anyone had already the same kind of problem but it seems not. I guess that the solution is to build a bond term in the definition of the Hamiltonian by specifying the source and targets and to modify accordingly the lattice. Or is there a trick to specify one source (i) and two targets (i+1, i-1) ?

Thanks in advance, Julien

Ps : Just realized that I forgot to modify the subject (short vacations ...)