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From: Matthias Troyer <troyer@phys.ethz.ch>
To: comp-phys-alps-users@lists.phys.ethz.ch
Sent: Sat, December 18, 2010 12:51:18 PM
Subject: Re: [ALPS-users] anisotropic Heisenberg model setup

Indeed, J is just a short cut for J0. Thus if you only set J, then J1=0

Matthias

On Dec 18, 2010, at 4:50 PM, Ruben Ghulghazaryan wrote:

> Hi ALPS team,
>
> I am trying to make simple simulations with anisotropic Heisenberg model on a ladder with ALPS2 rc2.
>
> According to models.xml and full diagonalization web page if I specify  J0 and J1 parameters then for different bond types "0" and "1" I will have J0 and J1 coefficients in Heisenberg ("spin") model.
> I did a simple experiment by performing fulldiag two simulations: one by using J=1 and the other J0=1,J1=1 and compared the results.
>
> I expected that the results should be the same according to "spin" model definition: defaults for J0and J1 is J if they are not specified. But I found that the results of energy and other quantities are different.
> below are my two parameter files:
>
>  LATTICE="ladder"
> MODEL="spin"
> local_S = 1
> J      = 1
> CONSERVED_QUANTUMNUMBERS="Sz"
> {L = 4}
>
> ++++++++++++++++++++++++
>
> LATTICE="ladder"
> MODEL="spin"
> local_S = 1
> J0      = 1
> J1      = 1
> CONSERVED_QUANTUMNUMBERS="Sz"
> {L = 4}
>
> ==========================
> I run fulldiag then fulldiag_evaluate
>
> fulldiag_evaluate --T_MIN 0.1 --T_MAX 10 --DELTA_T  0.1  parm6a.task1.out.xml
>
> as given in the web page
> http://alps.comp-phys.org/mediawiki/index.php/ALPS_2_Tutorials:ED-06_FullDiagonalization
>
> Would you please help me to understand why the results are different?
>
> Thanks,
> Ruben
>
>
>