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XY
by vitbka konef 09 Mar '17

09 Mar '17

Dear all. I am trying calculate the energy of the spin model for Jxy=1 and Jxy=-1. Why that energy does not depend on the sign of the Jxy (worm , dirloop_sse , fulldiag)? Best wishes.

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Extracting the data of local density
by youchamianshidai＠sina.com 01 Mar '17

01 Mar '17

Dear All: I have a problem with my calculations. I want to extract the density data of the same point in several periods, but I don't know how to solve it. I can only extract the data of all grid points. If anyone knows, I hope you can tell me. I would be very grateful! Best wishes

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diagonal correlations
by Robertson Esperanza 07 Feb '17

07 Feb '17

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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Help With QWL Measurements
by Lucas Menicucci 02 Feb '17

02 Feb '17

Good Afternoon, I`d like to know how to have access to the density of states's g(n)`s histogram on the Quantum Wang-Landau simulation. I`ve searched over http://alps.comp-phys.org/mediawiki/index.php/Documentation:qwl#Measurements and the source code but could`t find where the histogram`s data is written. Any help would be appreciated. Thank You, Lucas Menicucci.

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fermion vs alternative fermion
by Robertson Esperanza 31 Jan '17

31 Jan '17

Hello, Thank you for all the previous help. Checking models.xml file i can see two SITEBASIS named "fermion" and "alternative fermion". What are their differences?

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XML tag expected
by Larry Engelhardt 22 Jan '17

22 Jan '17

Dear ALPS list, I was very excited to see that the new version of ALPS was available for installation via conda! I did the conda installation, and I attempted to run the simple simulation pasted at the bottom of this email (taken from the ALPS webpage). The code started to execute, and the input files were created (parm1.in.xml, parm1.task1.in.xml, parm1.task2.in.xml, parm1.task3.in.xml). Then the message "parsing task files ..." was immediately followed by the message "XML tag expected". Each of the four XML input files start with the following two lines: <?xml version="1.0" encoding="UTF-8"?> <?xml-stylesheet type="text/xsl" href="ALPS.xsl"?> I'm sure that there must be a very simple cause for this problem. Can anyone diagnose this for me? Thanks! Larry CODE: import pyalps parms = [] for t in [1.5,2,2.5]: parms.append( { 'LATTICE' : "square lattice", 'T' : t, 'J' : 1 , 'THERMALIZATION' : 1000, 'SWEEPS' : 100000, 'UPDATE' : "cluster", 'MODEL' : "Ising", 'L' : 8 } ) input_file = pyalps.writeInputFiles('parm1',parms) pyalps.runApplication('spinmc',input_file,Tmin=5),writexml=True)

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Conserve quantum number for composite unit cell
by Axel Gagge 18 Jan '17

18 Jan '17

?Hello, I just wanted to ask if it is possible to preserve a combination of quantum numbers such as the total number of excitations: N = \sum_{bosonic sites} n_j + 1/2 \sum_{spinful sites} s_z and what the syntax for this would be? I guess that one option would be to define a new quantum number and let Splus raise it by 1/2 but I just thought that I would check this with you first! Otherwise, thank you for an excellent library! I have had no problems so far with the new release. Thanks, /Axel Gagge First year PhD Student, Stockholm University

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mps_optim: measurement - bug?
by Mateusz Łącki 18 Jan '17

18 Jan '17

Dear All. I would like to report a likely bug. I play with a simple transverse ising model for S=1/2. I take a short chain of length say 8, compute magnetization in x and z direction. When I compute the same input with mps_optim and sparsediag i obtain different results. Both codes give me different magnetizatios in mps_optim measurement seems to be wrong by a factor. I changed the definition of a default model “spin” (see below), the coupling is along x axis and field is along z. I consider the following input: LATTICE="inhomogeneous chain lattice" MODEL_LIBRARY="models.xml" MODEL="spin" J=1 SWEEPS=8 chkp_each=8 MEASURE_LOCAL[Local magnetization Xa]=Splus MEASURE_LOCAL[Local magnetization Xb]=Sminus MEASURE_LOCAL[Local magnetization X1]=Sx MEASURE_LOCAL[Local magnetization X2]=Sxx MEASURE_LOCAL[Local magnetization Z]=Sz MAXSTATES=40; NUMBER_EIGENVALUES=1; {h=0;Gamma=0;L=8} ******************* In the above the Sxx operator is defined exactly the same as Sx: <SITEOPERATOR name="Sx" site="x"> 1/2*(Splus(x)+Sminus(x)) </SITEOPERATOR> but with 1/4 factor, not 1/2: <SITEOPERATOR name="Sxx" site="x"> 1/4*(Splus(x)+Sminus(x)) </SITEOPERATOR> There are 2 runs that are important for my message: RUN A): running the above input with sparsediag gives (at any site): Local magnetization Xa=0.5 Local magnetization Xb=0.5 Local magnetization X1=0.5 Local magnetization X2=0.25 Which makes sense, as Sx=0.5*(Jplus + Jminus) RUN B): running the above input with mps_optim gives (at any site): Local magnetization Xa=0.5 Local magnetization Xb=0.5 Local magnetization X1=1.0 Local magnetization X2=1.0 My conclusion: It seems that measurement ignores the factor 1/4 in the definition of Sxx and 1/2 in the definition of Sx. If it is indeed the case (not stupid mistake on my side), would it be possible to issue a patch? If I change <BONDTERM source="i" target="j"> <PARAMETER name="J#" default="J"/> -J#*Sx(i)*Sx(j)*4 </BONDTERM> into <BONDTERM source="i" target="j"> <PARAMETER name="J#" default="J"/> -J#*Sxx(i)*Sxx(j)*4 </BONDTERM> then I get a correct factor 4 reduction in energy. So it seems only the mesurement ignores the numerical factor. If I exchange x-z direction in the Hamiltonian everything seems fine. Best, Mateusz Łącki

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The questions of ALPS application
by youchamianshidai＠sina.com 18 Jan '17

18 Jan '17

Dear professors: I am a beginner of ALPS. In my research, I have a very difficult problem, we need to calculate the density of each point on the lattice, but I don't know how to calculate. I would appreciate your help if you could tell me how to calculate it. Thank you again for viewing my mail.Best wishs to you. Thank you

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New ALPS release 2.3.0
by Michele Dolfi 16 Jan '17

16 Jan '17

Dear all, Version 2.3.0 of ALPS has been released. The main changes compared to the previous release are: - Support for Boost > 1.58 - Support for Mac OS 10.10 and 10.11 - Support for Python 3 (only with Boost >= 1.63.0) - Distribution of binaries via Conda-Forge (Linux, Mac, Win) - Distribution via Docker image - Fixes and features in MPS codes - Fixes and features in Graph library - Fixes and features in DWA - Other minor fixes The source distribution is available on the ALPS website https://alps.comp-phys.org/mediawiki/index.php/Download_and_install_ALPS_2 <https://alps.comp-phys.org/mediawiki/index.php/Download_and_install_ALPS_2> + For new users relying on the binary installation we recommend the cross-platform Conda distribution. + For computational clusters we now provide EasyBuild recipes on the official EasyBuild repository. We encourage the use of these recipes. Some distributions already contain the new version, others will be updated in the next days. We tried to test on as many systems as we could, but some bugs might still be present. Do not hesitate to write in case you have problems installing or running the release. We will schedule some minor release to address your issues. Best regards, Michele -- ETH Zurich Dr. Michele Dolfi Institute for Theoretical Physics HIT G 32.4 Wolfgang-Pauli-Str. 27 8093 Zurich Switzerland dolfim(a)phys.ethz.ch www.itp.phys.ethz.ch +41 44 633 78 56 phone +41 44 633 11 15 fax

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