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: 1. Copy the file models.xml from ALPS_ROOT/lib/xml/models.xml, where ALPS_ROOT is the root location of your alps installation.
2. Add this definition to your local copy, it defines the n^2 operator <SITEOPERATOR name=“n_squared" site="x"> n(x)*n(x) </SITEOPERATOR>
3. In your input parameters you have now to link to your new model file. MODEL_LIBRARY=“path/to/models.xml”
4. 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
+41 44 633 78 56 phone +41 44 633 11 15 fax
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
Comp-phys-alps-users Mailing List for the ALPS Project http://alps.comp-phys.org/
List info: https://lists.phys.ethz.ch//listinfo/comp-phys-alps-users Archive: https://lists.phys.ethz.ch//pipermail/comp-phys-alps-users
Unsubscribe by writing a mail to comp-phys-alps-users-leave@lists.phys.ethz.ch.