- Comp-phys-alps-users - lists.phys.ethz.ch

confusion
by Negin Mohseni 23 Feb '20

23 Feb '20

Dear Developer, I have been confused!!! I wish to ask a question about ALPS from everyone who can help me. How can I send my question? I have been subscripted in ALPS and I have received Comp-phys-alps-users Digest I do not know how I can send my question

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Conserved quantities in the Hubbard model
by Robertson Esperanza 17 Jan '20

17 Jan '20

Hi, It is known that the number of spin-up and spin-down electrons are conserved quantities in the Hubbard model. I just noticed that in the mps_optim paper (Computer Physics Communications 185 (2014) 3430-3440) that the example for the hubbard ladder has Nup_total and Ndown_total are the same even if the system is away from half-filling. Is this a general property of the model's ground state? If so, I would like to know references pertaining to this property. Related to that is, if I used the alternative fermionic hubbard model, is the property mentioned above the same as setting Sz_total = 0? Thanks, Robertson C. Esperanza

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Running ALPS on Conda
by tao.liu＠riken.jp 07 Aug '19

07 Aug '19

Dear Developer of ALPS project and All, I am a new user of ALPS package. I have installed the ALPS package via Conda with python2.7 environments. Although the package is successfully installed. But when I run the example file “tutorial-full.py” with spyder IDE integrated in anaconda, an error occurs, which says: =================================================================== File "C:\Users\Anaconda3\envs\python2\lib\site-packages\pyalps\tools.py", line 285, in xslPath return pyalps.pytools.search_xml_library_path("ALPS.xsl").replace(b'\0', '') RuntimeError: Cannot find file ALPS.xsl, failed to find it at /lib/xml\ALPS.xsl====================================================================================It seems that I should set the environment variable ALPS_XML_DIR to the correct path. But could you please teach me how to set the environment variable ALPS_XML_DIR ? The "ALPS.xsl" file is located in "\Anaconda3\envs\python2\Library\lib\xml\". Thanks very much! Best regards Tao LIU

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Problems with exact diagonalization
by Tandon Swetanshu 04 May '19

04 May '19

Hi, I am trying to calculate the magnetic susceptibility at different temperatures for two coupled dimers (similar to a part of tutorial ED-06) using exact diagonalisation. I have been previously using a code called PHI (http://www.nfchilton.com/phi) and an in-house code that can also perform exact diagonalisation. The result I obtain from both the in-house code and PHI are the same but they are different from the ones that I obtain from ALPS using the same parameters. I am not sure why that is the case. The input parameters and the output obtained are in the attached files. For the Zeeman term, I assumed that h is the product of h and g but I have calculated the susceptibility at both h=0.1 and h=0.202 (assuming g=2.02) with ALPS. Can you please guide me as to what am I doing wrong? Best regards, Swetanshu.

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Suggestion for improving doc Anaconda install
by Jessica Alfonsi 24 Apr '19

24 Apr '19

Dear all, lately I have come back after a long break to ALPS libraries and I have checked the website for installing these libraries via Conda on Linux in the quickest way. I find it should be made clearer that ALPS rely on Python 2.7 and that you should install as first step at least Miniconda2 which provides Python 2.7. I knew this just because I always kept reading mailing digest but it's not evident from the official website and this may create confusion. In the meantime, until Python 2.7 is not completely dropped and ALPSCore is matured, I suggest to provide ALPS binaries based on Python 3.7 or higher. Best regards, Jessica

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Finite temperature calculation using MPS
by Manpreet Singh 24 Mar '19

24 Mar '19

Dear ALPS users, I wish to do finite temperature calculations for the Bose-Hubbard model. Is it possible to do so using the ALPS MPS application? Any help will be appreciated. Regards- Manpreet

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Question about Kondo lattice model 2
by riku.masui＠yukawa.kyoto-u.ac.jp 28 Feb '19

28 Feb '19

Dear ALPS users and developers, I solved the problem which I sent to this mailing list on February 1st by myself, but I got another problem about Kondo lattice model. I am studying one dimensional Kondo lattice model with ALPS DMRG application, and in a small system(L=4),I compared the ground state energy which I got by ALPS DMRG with the one which I got by exact diagoanlization in the case t=0,J=1 and I fixed the number of conduction electrons 4(i.e. half-filled).Then I got E0=-1.6160254... by DMRG and E0 =-3.00000...by exact diagonalization. The latter seems to be reasonable, but I don't have any idea about where DMRG is wrong. I used ALPS lattice library and "2 band open chain lattice", and the model library to which I added a quantum number "N" and a constraint in order to fix the number of conduction electrons. I have attached the model library xml file to this email. And I used the following parameter file: 'LATTICE' : "2 band open chain lattice", 'MODEL_LIBRARY' :"kondo_lattice_ model.xml", 'MODEL' : "Kondo lattice ", 'CONSERVED_QUANTUMNUMBERS' :"N", 'N_total' :4, 'local_spin' :0.5, 't' :0, 'J' :1, 'SWEEPS' : 6, 'NUMBER_EIGENVALUES' : 2, 'L' : 4, 'MAXSTATES' : 150 Any advice will help me. Best regards, Riku Masui

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Question about Kondo lattice model
by riku.masui＠yukawa.kyoto-u.ac.jp 01 Feb '19

01 Feb '19

Dear ALPS users and developers, I am a beginner of ALPS and English writing. I am studying Kondo lattice model with alps dmrg application for python. I tried to calculate correlation functions <S(i)S(j)> between local spins using 'Kondo lattice' model and '2 band open chain lattice' ,which are in alps lib and I didn't change anything. And I used the following parameter file: parms = [ { 'LATTICE' : '2 band open chain lattice', 'MODEL' : 'Kondo lattice', 'local_S' :0.5, 't' : 1, 'J' : 1, 'SWEEPS' : 4, 'NUMBER_EIGENVALUES' : 1, 'L' : 32, 'MAXSTATES' : 300, 'MEASURE_CORRELATIONS[Momentumup]' :'cdag_up:c_up', 'MEASURE_CORRELATIONS[Momentumdown]' :'cdag_down:c_down', 'MEASURE_AVERAGE[Magnetization]' : 'Sz', 'MEASURE_AVERAGE[Exchange]' : 'exchange', 'MEASURE_LOCAL[Local magnetization]' : 'Sz', 'MEASURE_CORRELATIONS[Diagonal spin correlations]' : 'Sz', 'MEASURE_CORRELATIONS[Offdiagonal spin correlations]' : 'Splus: Sminus' } ] However, dmrg doesn't run and returned the error "Cannot evaluate expression c_down(j)". This might be a foolish question, but I have no idea. So, could you give me some advice? Any advice will help me. Best regards, Riku Masui

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DWA convergence problem
by Oskar Amadeusz Prośniak 22 Jan '19

22 Jan '19

Dear all, while performing some simulations in BH model (DWA code), I encountered problems with convergence in the vicinity of the critical point for small temperature T and a large linear dimension L. What is the root cause for the complexity of the simulation in such a case? I seem to get a large systematic error (which looks non-random as a a function of hamiltonian coupling constants). Is there any way to improve convergence? While searching output hdf5 files for additional clues, and the DWA documentation, I have encountered the error_convergence in output files. Could I ask what exactly it is? Is it related to the "binning analysis" which has been discussed throughout the alps website? Is there is a build-in method for convergence analysis? that would be very helpful. Best regards, Oskar A. Prośniak

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'Nonlocal' in the worm QMC
by 郭怀明 13 Jan '19

13 Jan '19

Dear all, I have a problem related to the worm QMC. I find there is a parameter 'nonlocal', which is set to 0 in the examples. I wonder what is the meaning of the parameter. Is it a systematic parameter for the method? Thank you for your reply. Sincerely, Huaiming Guo Beihang Unviersity

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