[ALPS-users] Local measurements in ALPS

[Axel Gagge]

If there is any more information I can provide to make the problem more clearly formulated? I am looking to measure the operator "n" after a DMRG calculation (mps_optim). 

'n' is defined on sites labeled by even integers, and I expected the command 'MEASURE_LOCAL_AT' to work for measuring local expectation values.

I am adding the following to my parameter file as of the moment:

parms[0]['MEASURE_LOCAL_AT[n_0]'] = "n|(0)"

I include the relevant files I can think of. If you are working on the issue or if I have failed to provide enough information, I apologize.

Many thanks,
/Axel

________________________________________
Från: Comp-phys-alps-users <comp-phys-alps-users-bounces at lists.phys.ethz.ch> för Axel Gagge <axel.gagge at fysik.su.se>
Skickat: den 21 februari 2017 18:56
Till: comp-phys-alps-users at lists.phys.ethz.ch
Ämne: Re: [ALPS-users] Local measurements in ALPS

I attached the input/output XML file. I am using the DMRG application. I am trying to measure a local expectation value which is only defined on one of the two cells in the unit cell. Also, I can't seem to get out the energy variance or entropy at all, maybe I'm not specifying it in a correct way.

Many thanks,
Axel

________________________________________
Från: Comp-phys-alps-users <comp-phys-alps-users-bounces at lists.phys.ethz.ch> för Michele Dolfi <dolfim at phys.ethz.ch>
Skickat: den 21 februari 2017 17:48
Till: comp-phys-alps-users at lists.phys.ethz.ch
Ämne: Re: [ALPS-users] Local measurements in ALPS

I don't really get what you are trying to do, could you attach some
input file?
Are you using the dmrg application or mps_optim?


Best,
Michele


On 2017-02-21 13:21, Axel Gagge wrote:
> I am trying to do local measurements on a DMRG state, and thought of
> using (using Python):
>
>
> parms[0]['MEASURE_LOCAL_AT[n_0]'] = "n|(0)"
>
>
> In this case the operator "n" should have support only on the sites
> labeled by even integers, but the DMRG run does not return any output.
> Trying 'MEASURE_LOCAL' of course returns something like "operator n
> not recognized" since it does not work for odd sites.  Is the output
> not supposed to be included with
> "pyalps.loadEigenstateMeasurements()"?
>
>
> Is there a way to measure local properties (and correlation functions)
> between even sites only?
>
> Can (and should) operators be defined on the unit cell as well as the
> sites?
>
>
> /Axel Gagge
>
>
>
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--
ETH Zurich
Michele Dolfi
Institute for Theoretical Physics
HIT G 32.4
Wolfgang-Pauli-Str. 27
8093 Zurich
Switzerland

dolfim at phys.ethz.ch
www.itp.phys.ethz.ch

+41 44 633 78 56 phone
+41 44 633 11 15 fax


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