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
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
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:
MEASURE_AVERAGE is compute the average among all sites, i.e. a scalar value. MEASURE_LOCAL returns a list of measurements on all sites.
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
When creating a new model file, is it necessary that the new model file be saved on the same folder of the default models.xml file?
On Mon, Feb 6, 2017 at 3:55 PM, Michele Dolfi dolfim@phys.ethz.ch wrote:
Hi,
you can do it in this way but in your parameter file you have to write :
model['MODEL_LIBRARY'] = 'my_own_models.xml'
or you can put it wherever you want but in this case :
model['MODEL_LIBRARY'] = 'path_to_the_xml_file'
Julien
On 06/02/2017 09:21, Robertson Esperanza wrote:
I tried to print the result of taking the local measurement for n_i^2 but it only shows x = [0], y = [0], instead of x = [0 1 2 3 4 5 6 7 8 9], y = [10 scalar values] (since i'm using a 10-site open chain). I attached my python script and mymodels.xml. Thank you for the help.
On Mon, Feb 6, 2017 at 4:29 PM, Julien julien.despres@institutoptique.fr wrote:
Hi,
there is a little problem in your python script; have a look to the line where you include the xml file for the models.
Julien
- __________________________________
DESPRES Julien Ph.D. student
Center for Theoretical Physics Quantum Matter Theory team Ecole Polytechnique 91128 Palaiseau Cedex France, EU Office : 00.10.06 (ground floor) Phone : +33 1 64 33 42 81
Laboratoire Charles Fabry Atom Optics group Institut d'Optique Graduate School 2 Avenue Augustin Fresnel 91127 Palaiseau Cedex France, EU Office : R2.29 (1st floor) Phone: +33 1 64 53 33 49 __________________________________
On 07/02/2017 04:24, Robertson Esperanza wrote:
-
I tested your file after modifying this line. It works
On 07/02/2017 09:01, Julien wrote:
the line where I put the file path of the xml file (i.e. 'MODEL_LIBRARY':) ?
On Tue, Feb 7, 2017 at 4:04 PM, Julien julien.despres@institutoptique.fr wrote:
yes, there is no path ...
Julien
On 07/02/2017 09:53, Robertson Esperanza wrote:
Yes, it is intended when I attached it, so it can be changed. When i run the script, I put the filepath, but I still get the x = [0], y = [0] result. Can I see what's the result when you run the script? Thank you for the help.
On Tue, Feb 7, 2017 at 6:53 PM, Julien julien.despres@institutoptique.fr wrote:
Hi,
Here is what I got, I met the same problem that you had; but I defined the observable as an operator in the hamiltonian and it seems to work ... You can check the results for different phases by playing with the hopping, the onsite interaction etc... and also if the number of states that you keep in the Schmidt decomposition is enough.
Ps : I'm a beginner so be careful
Julien
------------------------------
julien@Pegasus:~/Thesis/code_julien/dmrg/dmrg-01-dmrg$ ./../../../../../julien/Thesis/ALPS/install/bin/alpspython test.py mps_optim test_dens_corr.in.xml --write-xml /bin/sh: 1: mps_optim: not found [[x=[0 1 2 3 4 5 6 7 8 9] y=[[ 1.31501684 1.35161251 1.31271542 1.3228399 1.31463584 1.31463585 1.32283991 1.31271542 1.35161252 1.31501684]] props={'nsweeps': 10.0, 'NUMBER_EIGENVALUES': 1.0, 'lattice_library': 'alps', 'MAXSTATES': 100.0, 'L': 10.0, 'donotsave': 0.0, 'LATTICE': 'open chain lattice', 'chkpfile': '/home/julien/Thesis/code_julien/dmrg/dmrg-01-dmrg/test_dens_corr.task1.out.chkp', 'COMPLEX': 0.0, 'U': 0.0, 'CONSERVED_QUANTUMNUMBERS': 'N,Sz', 'V': 1.0, 'MODEL': 'extended fermion Hubbard', 'seed': 42.0, 'MEASURE_LOCAL[density_corr_diag]': 'n2', 'MODEL_LIBRARY': 'mymodels.xml', 'observable': 'density_corr_diag', 'run_seconds': -1.0, 'storagedir': 0.0, 'SWEEPS': 10.0, 'filename': './test_dens_corr.task1.out.h5', 'hdf5_path': '/spectrum/results/density_corr_diag', 'SEED': 868763985.0, 'model_library': 'alps', 'sweep_bond_dimensions': '20,28,37,46,55,64,73,82,91,100', 'N_total': 10.0, 'resultfile': '/home/julien/Thesis/code_julien/dmrg/dmrg-01-dmrg/test_dens_corr.task1.out.h5', 't': 1.0}, x=[0] y=[-15.06955933] props={'nsweeps': 10.0, 'NUMBER_EIGENVALUES': 1.0, 'lattice_library': 'alps', 'MAXSTATES': 100.0, 'L': 10.0, 'donotsave': 0.0, 'LATTICE': 'open chain lattice', 'chkpfile': '/home/julien/Thesis/code_julien/dmrg/dmrg-01-dmrg/test_dens_corr.task1.out.chkp', 'COMPLEX': 0.0, 'U': 0.0, 'CONSERVED_QUANTUMNUMBERS': 'N,Sz', 'V': 1.0, 'MODEL': 'extended fermion Hubbard', 'seed': 42.0, 'MEASURE_LOCAL[density_corr_diag]': 'n2', 'MODEL_LIBRARY': 'mymodels.xml', 'observable': 'Energy', 'run_seconds': -1.0, 'storagedir': 0.0, 'SWEEPS': 10.0, 'filename': './test_dens_corr.task1.out.h5', 'hdf5_path': '/spectrum/results/Energy', 'SEED': 868763985.0, 'model_library': 'alps', 'sweep_bond_dimensions': '20,28,37,46,55,64,73,82,91,100', 'N_total': 10.0, 'resultfile': '/home/julien/Thesis/code_julien/dmrg/dmrg-01-dmrg/test_dens_corr.task1.out.h5', 't': 1.0}]] --------------------------------
On 07/02/2017 17:04, Robertson Esperanza wrote:
Hi,
Here is what I got, I met the same problem that you had; but I defined the observable as an operator in the considered hamiltonian and it seems to work ... You can check the results for different phases by playing with the hopping, the onsite interaction etc... and also if the number of states that you keep in the Schmidt decomposition is enough.
Julien
------------------------------
julien@Pegasus:~/Thesis/code_julien/dmrg/dmrg-01-dmrg$ ./../../../../../julien/Thesis/ALPS/install/bin/alpspython test.py mps_optim test_dens_corr.in.xml --write-xml /bin/sh: 1: mps_optim: not found [[x=[0 1 2 3 4 5 6 7 8 9] y=[[ 1.31501684 1.35161251 1.31271542 1.3228399 1.31463584 1.31463585 1.32283991 1.31271542 1.35161252 1.31501684]] props={'nsweeps': 10.0, 'NUMBER_EIGENVALUES': 1.0, 'lattice_library': 'alps', 'MAXSTATES': 100.0, 'L': 10.0, 'donotsave': 0.0, 'LATTICE': 'open chain lattice', 'chkpfile': '/home/julien/Thesis/code_julien/dmrg/dmrg-01-dmrg/test_dens_corr.task1.out.chkp', 'COMPLEX': 0.0, 'U': 0.0, 'CONSERVED_QUANTUMNUMBERS': 'N,Sz', 'V': 1.0, 'MODEL': 'extended fermion Hubbard', 'seed': 42.0, 'MEASURE_LOCAL[density_corr_diag]': 'n2', 'MODEL_LIBRARY': 'mymodels.xml', 'observable': 'density_corr_diag', 'run_seconds': -1.0, 'storagedir': 0.0, 'SWEEPS': 10.0, 'filename': './test_dens_corr.task1.out.h5', 'hdf5_path': '/spectrum/results/density_corr_diag', 'SEED': 868763985.0, 'model_library': 'alps', 'sweep_bond_dimensions': '20,28,37,46,55,64,73,82,91,100', 'N_total': 10.0, 'resultfile': '/home/julien/Thesis/code_julien/dmrg/dmrg-01-dmrg/test_dens_corr.task1.out.h5', 't': 1.0}, x=[0] y=[-15.06955933] props={'nsweeps': 10.0, 'NUMBER_EIGENVALUES': 1.0, 'lattice_library': 'alps', 'MAXSTATES': 100.0, 'L': 10.0, 'donotsave': 0.0, 'LATTICE': 'open chain lattice', 'chkpfile': '/home/julien/Thesis/code_julien/dmrg/dmrg-01-dmrg/test_dens_corr.task1.out.chkp', 'COMPLEX': 0.0, 'U': 0.0, 'CONSERVED_QUANTUMNUMBERS': 'N,Sz', 'V': 1.0, 'MODEL': 'extended fermion Hubbard', 'seed': 42.0, 'MEASURE_LOCAL[density_corr_diag]': 'n2', 'MODEL_LIBRARY': 'mymodels.xml', 'observable': 'Energy', 'run_seconds': -1.0, 'storagedir': 0.0, 'SWEEPS': 10.0, 'filename': './test_dens_corr.task1.out.h5', 'hdf5_path': '/spectrum/results/Energy', 'SEED': 868763985.0, 'model_library': 'alps', 'sweep_bond_dimensions': '20,28,37,46,55,64,73,82,91,100', 'N_total': 10.0, 'resultfile': '/home/julien/Thesis/code_julien/dmrg/dmrg-01-dmrg/test_dens_corr.task1.out.h5', 't': 1.0}]] --------------------------------
On 07/02/2017 17:04, Robertson Esperanza wrote:
comp-phys-alps-users@lists.phys.ethz.ch