---

From: Ryo IGARASHI <rigarash@hosi.phys.s.u-tokyo.ac.jp>
To: comp-phys-alps-users@lists.phys.ethz.ch
Sent: Wed, December 22, 2010 7:28:46 AM
Subject: Re: [ALPS-users] Fw: anisotropic Heisenberg model setup

Hi, Ruben,

On Tue, Dec 21, 2010 at 5:31 PM, Ruben Ghulghazaryan <ghulr@yahoo.com> wrote:
> This is simply wrong. J=1 just means J0=1. As Matthias said, all the J1 term
> is 0 (J1=Jz1=Jxy1=0) when only J=1 is set.
>
> [Ruben]--->OK. Does it mean that all bond interaction terms will be the same
> both in horizontal and vertical directions?
> Or, does it mean we have only horizontal bonds with interaction J0=1 and
> vertical bonds terms = 0 and we have two non-interacting chains instead of a
> ladder?

Simply the latter case. Just check the result. You can check the result with
chain lattice.

The coupling on the vertical bonds are defined by J1. Check the
description of "ladder"
lattice in lattices.xml you use.

>> In the case we specify J0=1 and J1=1 again all bonds should get 1 as bond
>> term and the model results should be the same
>> as for setting J only. In this case both isotropic and anisotropic models
>> should give similar results.
>
> J0=1 and J1=1 give the symmetric ladder. And thus, you will get the same
> results
> if you specify a symmetric ladder (i.e. all coupling constant is same
> IN THE LATTICE DESCRIPTION) with J=1.
>
> [Ruben]--->
> I agree and this is what I expect too.
> I did an experiment with the following settings which as far as I understand
> both should set the same bond interaction term 1 for all bonds:
>
> (a)
> LATTICE="ladder"
> MODEL="spin"
> local_S = 1
> J       = 1
> CONSERVED_QUANTUMNUMBERS="Sz"
> {L = 4}
> ++++++++++++++++++++++++
> (b)
> LATTICE="ladder"
> MODEL="spin"
> local_S = 1
> J0      = 1
> J1      = 1
> CONSERVED_QUANTUMNUMBERS="Sz"
> {L = 4}
> ==========================
> I run fulldiag then fulldiag_evaluate
> fulldiag parm1.in.xml
> fulldiag_evaluate --T_MIN 0.1 --T_MAX 10 --DELTA_T  0.1  parm1.task1.out.xml
> The results of these two runs are different. I can not understand why the
> results should be different.
>
> Does (a) defines a ladder were both horizontal and vertical bond terms are
> equal 1?
> Does (b) defines a ladder were both horizontal and vertical bond terms are
> equal since J0=J1=1?
> Please see the file attached for illustration.
> If these two parameter files use different settings but define the same
> lattice and model, then why the results of fulldiag runs are different?

I am repeatedly telling you that you should check the lattice description
of "ladder" in lattices.xml, which shows that bond types are different from
each other for horizontal and vertical bond.
So the short answer for your questions are:
(a) No.
(b) Yes.
(c) You are just simulating different setting.

Best regards,
--
Ryo IGARASHI, Ph.D.
rigarash@hosi.phys.s.u-tokyo.ac.jp
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