I'm using ALPS 1.3 version. Matthias Troyer <troyer@itp.phys.ethz.ch> wrote: Which version of ALPS do you use? ALPS 1.2 does not have support for translational symmetries yet. If you use a beta version ALPS 1.3 and turn on support for quantum numbers by specifying the input parameters CONSERVED_QUANTUMNUMBERS="Sz" then you will have the fastest possible code Matthias On 17 Oct 2006, at 06:38, Rakesh Kumar wrote: Dear all, If I want sparse diagonalize Heisenberg Hamiltonian of 4x4 site cluster on square lattice. How much time will be take ? I running this program 3748 minutes but till now it is not ended. It seems very time consumable. With Best regards Rakesh Kumar School of Physical Sciences, JNU, New Delhi-110067 (INDIA) Mob.No.: +91-9891397108 --------------------------------- Get your own web address for just $1.99/1st yr. We'll help. Yahoo! Small Business. With Best regards Rakesh Kumar School of Physical Sciences, JNU, New Delhi-110067 (INDIA) Mob.No.: +91-9891397108 --------------------------------- Access over 1 million songs - Yahoo! Music Unlimited.