Comp-phys-alps-users

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1244 discussions

what is the classic monte carlo algorithm?
by sh sh 12 Dec '12

12 Dec '12

Dear friends Would you mint telling me what is the classic MC algorithm in codes of alps python? And , Is the "T" in units of J/KB , in the plots which are versus T, forexample sprcific heat ? thanks for your help

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maxent
by dt331＠bath.ac.uk 12 Dec '12

12 Dec '12

Dear All, I would like to attempt the analytic continuation of greens function produced by TRIQS to obtain the spectral function. I have installed the maxent tool, but can not find how to use it. Can anyone show me some example input files and other information on its functioning? A reference on the method would also be useful. Thanks, David Tompsett.

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help for one code
by sh sh 08 Dec '12

08 Dec '12

Hi friends.I am practicing tutorial and I faced one code for doing one plot with all data like this: #load the binning analysis for the absolute value of the magnetization binning = pyalps.loadBinningAnalysis(pyalps.getResultFiles(prefix='param'),'|Magnetization|') binning = pyalps.flatten(binning) #make one plot with all data for dataset in binning: dataset.props['label'] = 'L='+str(dataset.props['L']) plt.figure() plt.xlabel('binning level') plt.ylabel('Error of |Magnetization|') pyalps.plot.plot(binning) plt.legend() plt.show() Now I have 2 question: 1. I can not understand what is the meaning of : " dataset.props['label'] = 'L='+str(dataset.props['L'])",what is its meaning? 2. And also if I wanna plot energy versus temperature , which part of the above code must be changed ? thanks alot for your help

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question for extracttext
by sh sh 07 Dec '12

07 Dec '12

Hi friends.I am learning working with alps so I test the codes that is written in website for classic monte carlo simulation.I wrote those codes on my terminal but when I arrive to codes below: extracttext plot.xml parm2a.task*.out.xml extractxmgr plot.xml parm2a.task*.out.xml > plot2a.xmgr xmgrace plot2a.xmgr it gives error and in my terminal it said that /opt/alps/bin/xslttransform: 16: exit: Illegal number: -1 /opt/alps/bin/xslttransform: 16: exit: Illegal number: -1 /opt/alps/bin/xslttransform: 16: exit: Illegal number: -1 so what shoul i do? also how can I install xmgrace for the above code?

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question
by sh sh 07 Dec '12

07 Dec '12

Hi friends,sorry when I run "extracttest" program , I face the error that say: Could not find XSLT transformer. Please set the ALPS_XSLT_TRANSFORMER environment variable what does it mean?what can I do?

1 0

3D quantum magnet
by Forwordom 07 Dec '12

07 Dec '12

Hi everyone I want to know if dirloop_sse QMC can simulation 3D finite size lattice such as magnetic clusters using Heisenberg model.

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eigenvectors of T-matrix
by jessica.alfonsi＠unipd.it 06 Dec '12

06 Dec '12

Dear ALPS developers, is it possible to have the coeffcients and eigenvectors of the T-matrix returned from lanczos object in lanczos.h ? I need them (the first component to be exact) for computing the spectral function. I do see the member function t_eigenvectors() in the header, but I wouldn't know exactly how to write the code to get the values since I'm not much into C++. Could you please add a couple of lines of code later to one of the lanczos examples, so it can be helpful for all users ? Best regards, Jessica Alfonsi

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Subject: Re: Sign problem
by Forwordom 06 Dec '12

06 Dec '12

Hi Matthias Thanks a lot for your reply. Yes, a nonzero EPSILON is only make the updates ergodic but can not eliminate sign problem. I cannot understand what your said "one can get rid of a sign problem by changing the basis". Actually, I have no any experience to modify or add codes in original ALPS codes. So I have to ask for you help. Now I send my lattice model and Hamiltonian model files to you. The used model is a coupled two ladder lattice with five exchange coupling constants in Heisenberg model Humiltonian.You can find those details in attachments. Two attach files can be found in attachments including my_ctwoladder_lattice describles lattice model and my_models describles the used model Humiltonian. Your reply will be highly appreciated. Forwordom

1 0

Sign problem
by Forwordom 05 Dec '12

05 Dec '12

Hi ALPS users and developers I meet sign problem in simulating frustrated system using dirloop_sse quantum Monte Carlo. As for this problem, the tutorial give some suggestions taht one should adjust parameter EPSILON and check the results carefully. But there is not the details of how to adjust this parameters. I have tried to modify all kinds of parameters including EPSILON,WHICH_LOOP_TYPE and so on. However the warning "the hamiltonian has sign problem" always appears when running. Can I get reliable the results when sign problem exists? How to modify simulation parameters to avoid sign problem using dirloop_sse method for my simulating frustrated systems. Can you give help. Thanks advanced.

2 1

question
by sh po 04 Dec '12

04 Dec '12

Hi friends.Recently I installed Alps on my ubuntu linux . sorry but I read your site carefully but it was so difficult for me to understand the way of working with alps.Because Im not professional enough in linux. I have 2 question from you 1.I was wondering if you'd mind giving me a text file (for example pdf) which explains way of working with alps in an easy and complete way. 2.My other question is that where should I type the codes that you wrote in your site? I mean should I copy and past them in my terminal? or copy and past them in a text filr which I open with "gedit" in linux?If a text file, so with what type I must save that text file?and after that with what compiler I must run it on my terminal? thanks alot for your help.

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