Dear Zhenya,
Many thanks!! It is not ugly it is beautiful and it works !!
All the best
jakub
> Message: 3
> Date: Fri, 27 Mar 2009 21:48:00 +0100
> From: Evgeny Burovskiy <burovski(a)alumni.umass.edu>
> Subject: Re: [ALPS-users] working on alps code
> To: comp-phys-alps-users(a)phys.ethz.ch
> Message-ID: <49CD3B80.9080803(a)physik.uni-greifswald.de>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
>
> Dear Jakub,
>
> > So I guess from examples .. but I cannot guess everything. To be specific.
> > I run QMC codes for Bose-Hubbard. I know how to get occupation at different
> > sides (for inhomogenous model, e.g. with harmonic trap and/or disorder),
> > call them <n_i>. But I am interested in second moment <n_i^2>
> >
> >
>
> There is a solution which looks ugly, but works :
>
> patch the definition of the site basis of the model you're working
> with.
> In your example, Bose-Hubbard Hamiltonian uses the basis called
> "boson".
> Go to models.xml file and then add a line to the SITEBASIS definition:
>
> <SITEBASIS name="boson">
> <PARAMETER name="Nmax" default="infinity"/>
> <QUANTUMNUMBER name="N" min="0" max="Nmax"/>
> <OPERATOR name="bdag" matrixelement="sqrt(N+1)">
> <CHANGE quantumnumber="N" change="1"/>
> </OPERATOR>
> <OPERATOR name="b" matrixelement="sqrt(N)">
> <CHANGE quantumnumber="N" change="-1"/>
> </OPERATOR>
> <OPERATOR name="n" matrixelement="N"/>
> <OPERATOR name="n2" matrixelement="N*N"/> <!-- added -->
> </SITEBASIS>
>
> Like I said, it's ugly, but it works.
> And, like you, I'd be very much interested in learning how to add
> measurements properly, without dirty tricks :).
>
>
> Best,
>
>
> Zhenya
>
>
> End of Comp-phys-alps-users Digest, Vol 36, Issue 16
> ****************************************************