Oh, I forgot to mention that I'm using mps_optim application. How does the result of MEASURE_AVERAGE differ from MEASURE_LOCAL, if let's say I use "n" for these parameters? Thanks
On Mon, Feb 6, 2017 at 3:08 PM, Michele Dolfi dolfim@phys.ethz.ch wrote:
Hello,
Could you please be a bit more specific about the application you are running?
You are right about the local measurement, but you need MEASURE_LOCAL, since you want to value at each site. Since the n_i^2 operator is not yet defined in the model library, you need to add it yourself. Basically I would do as follow:
- Copy the file models.xml from ALPS_ROOT/lib/xml/models.xml, where
ALPS_ROOT is the root location of your alps installation.
- Add this definition to your local copy, it defines the n^2 operator
<SITEOPERATOR name=“n_squared" site="x"> n(x)*n(x)
</SITEOPERATOR>
- In your input parameters you have now to link to your new model file.
MODEL_LIBRARY=“path/to/models.xml”
- And add your measurement
MEASURE_LOCAL[Density^2] = “ n_squared"
Hope this helps.
Best, Michele
-- ETH Zurich Dr. Michele Dolfi Institute for Theoretical Physics HIT G 32.4 Wolfgang-Pauli-Str. 27 8093 Zurich Switzerland
dolfim@phys.ethz.ch www.itp.phys.ethz.ch
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On 6 Feb 2017, at 07:26, Robertson Esperanza robbie.esperanza@gmail.com wrote:
Hello,
I only started studying many-body physics, so there might be gaps in my knowledge. When using the MEASURE_CORRELATION, why does the measurement goes for only site i<j, is it because there will be "blowing up"?
Alternatively, to measure for i=j, i think I could use MEASURE_AVERAGE, of let's say (n_i)^2 where n - n_up + n_down. How could I define such measurement, where you use an operator successively? Thank you for replying
Robertson Esperanza
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