Dear Zhian,

The energy does not depend on the algorithm. A finite system will always have an energy that is different than the energy in the thermodynamic limit, no matter what method you use. What you have to do is a finite size scaling. Plot the energies as a function of 1/L and extrapolate to zero, to get an estimate, and then compare that value to the Bethe anzats result.

Saludos, <ADRIAN>

zhian asadzadeh wrote:

Hi Dears I have got following results:" for open boundary condition" SWEEP=8, MAXSTATES=400, L=200, E0= -0.44220777784 SWEEP=50, MAXSTATES=500, L=200, E0= -0.4422077778446504 SWEEP=8, MAXSTATES=150, L=600, E0= -0.442833001737 SWEEP=8, MAXSTATES= 500, L=600, E0=- 0.44283300822 SWEEP=8, MAXSTATES= 150, L=700, E0= -0.442877

We see that the result still have not got to -0.443147.maybe we increase the size ,getting to this energy but it takes a lot of time . for periodic boundary condition the energy that achieved is lower. I have a question. Are there some techniques for use of this algorithm such that, for example, for 100 or 200 sites we get to the desire energy?