January 2013 - Comp-phys-alps-users

TEBD and custom lattices
by Deepak Iyer 21 Jan '13

21 Jan '13

Hi I'm trying to define a custom lattice to use with the tebd code. I've tested the lattice with sparsediag and it works as I want it to. However, TEBD seems to completely ignore any information about the lattice. It seems to look at only the model, and I guess assumes an open chain of length L with only nearest neighbor hopping. Is there a way to get around this? Thanks! Deepak

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site and bond-operators in the models.xml file
by Deepak Iyer 20 Jan '13

20 Jan '13

Hi I'm confused as to how the system knows what i and j should be (like nearest neighbor, next nearest, etc) for a particular model, since the bond-operators just go from i to j. Also, when there are wild cards in parameters, e.g., mu# in the boson Hubbard Hamiltonian, where are the different types defined? Do I need to define a new lattice type to allow for spatially varying mu, e.g.? Thanks Deepak

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Quenching 'L' in TEBD code
by Deepak Iyer 19 Jan '13

19 Jan '13

Hi I'm trying to quench 'L' in the TEBD code in the Bose-Hubbard model. I start with L=2 and quench to L=10. I'm interested in looking at what happens to the local occupation numbers. But the code only outputs 'Local Number' for 2 sites. I'm using an L=2 initial state to force the system into a particular initial state. I see that this is a bit ambiguous since its not clear what 'L' is midway in the quench, but is there any way I can get occupation for all 10 sites after the completion of the quench? I first quickly quench it and then hold the quench at a fixed U and L for sometime. Thanks! Deepak

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tebd hardcoded measurements
by Deepak Iyer 18 Jan '13

18 Jan '13

Hi I've been trying to find some documentation on hardcoded measurements in the tebd code. The docs don't seem to have anything. I did end up looking in the fortran code and found something but I am not sure how these things are defined. Would be great if there's some doc sitting somewhere on this. Thanks! Deepak

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Winding number histogram
by "Michał Maik" 12 Jan '13

12 Jan '13

Hi all, I was curious if there is an easy way to get the winding number histogram from both the worm code as well as the SSE code. I noticed that in the files Wmeas.C and evaluate.C there are references to the winding number histogram. What do I need to write in the parameter file to be able to get values of this histogram? In advance, thank you. Best Regards Michal Maik

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retrieving eigenvectors from sparsediag
by Rafał 09 Jan '13

09 Jan '13

Dear Alps Team and all Alps users I am trying to recreate results from the paper of Yi-Fei Wang , Zheng-Cheng Gu , Chang-De Gong and D. N. Sheng (please see http://arxiv.org/abs/1103.1686v1) I have already implemented a model into xml file and successfully generated phase diagram for 24 sites checkerboard model (FIG 1 (b)). Now I plan to calculate Berry curvature and Chern number (please see the FIG. 3 (c) and paragraph below it). And there comes my problem: I'm little confused how to calculate F(θ1 , θ2) [ F(\theta_1,\theta_2) ]. I have an idea how to calculate differentiation of the eigenvectors numerically and then calculate dot product but I don't know how to access to eigenvectors from sparsediag. I would be grateful for any advice. Best wishes Rafał Skolasiński

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Re: [ALPS-users] installing ALPS 2.1.1 on win7 and Mac
by Ben LI 03 Jan '13

03 Jan '13

Dear ALPS members and developers: I have been trying to install ALPS 2.1.1 (Binary package) on windows 7 (32-bit) and Mac OS X 10.6.8 (64-bit), but I met same problem when I open VirTrails: CRITICAL 2013-01-03 12:00:29,721 /Applications/VisTrails/VisTrails.app/Contents/Resources/lib/python2.7/core/packagemanager.py, line 501 Dependencies of package ALPS are missing so it will be disabled Package 'ALPS' has unmet dependencies: edu.utah.sci.vistrails.control_flow edu.utah.sci.vistrails.vtlcreator I will appreciate if you could help me fix the problem. Best regards, Ben LI

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questions about wavefucntion
by 黄口口 01 Jan '13

01 Jan '13

Dear alps users: Now I am learning ALPS. It's useful for me. But I have question: How to get the wave function or some calculation about it, for example, 1.the participation ratio(=1 / \sum_i ｜< i | \psi > |^4 ) 2.calculation of entropy. I search in the mail group, some people face the same difficulty, but I cannot find the answer, can any of you provide me the solution? Thank you! Best wishes to you! xin 2012.11.08

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question about sparsediag
by 陈巧妮 01 Jan '13

01 Jan '13

Hi, everyone When I use sparsediag to diagnalize the Hamiltonian of Hubbard model, the paprameter is : CONSERVED_QUANTUMNUMBERS="Nup,Ndown" Nup_total=6 Ndown_total=6 the system size is L=12, no translation symmetry here, the process will take 100s, which is much slower than our own Davison code(It only take 20s). if I add the measurements MEASURE_ENERGY="True" MEASURE_LOCAL[density]=n MEASURE_LOCAL[double occupancy]=U*double_occupancy MEASURE_CORRELATIONS[density matrix_up]="cdag_up:c_up" MEASURE_CORRELATIONS[density matrix_down]="cdag_down:c_down" the process will take 900s. Does anyone know how to speed up this calculation? Or at least avoid the waste time on the measurements -- Qiaoni Chen Department of Chemistry, Princeton University Princeton, NJ, 08544 Tel +1-609-865-0817

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Green's function measurement in the loop and directed loop codes
by Francisco Cordobés 01 Jan '13

01 Jan '13

Hello, I was wondering what is the definition that that the loop and directed loop code return when the options: 'MEASURE[Correlations]' : True, 'MEASURE[Structure Factor]' : True, 'MEASURE[Green Function]' : True, Because I haven't been able to find them and I would like to know what they are and more importantly what prefactors it has or it hasn't. Thank you very much, Francisco Cordobes

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