Hi. I'm a student doing research on Heisenberg spin chains, and I'm attempting to get ground state energies for longer chains than my group has done before. I've been running the DMRG program included with ALPS (not the 'simple' one) with a parameter file that looks something like:
MODEL = "spin" LATTICE = "chain lattice" LATTICE_LIBRARY = "../lattices.xml" MODEL_LIBRARY = "../models.xml" CONSERVED_QUANTUMNUMBERS = "Sz" local_S = 1/2 J = 1 V = 0 SWEEPS = 30 MAXSTATES = 60 OUTPUT_LEVEL = 1 {L = 30}
I've been able to successfully run the program, though I'm not entirely sure that all the parameters I've specified are the right ones (and that it's not just reverting to the defaults). I've been unable to find any documentation on how this particular implementation of the program works, so can anyone tell me if I'm off to the right start?
In addition, I'd like to be able to run this program with site-dependent interaction coefficients (such as J = 3*k) or so, but after much tinkering, I've been unable to find the variable 'k' that represents position on the lattice. My question is is this even possible? If so, how? Should I instead be trying to modify the source code for the program and recompile it?
Thanks for your time.