Comp-phys-alps-users December 2012

comp-phys-alps-users@lists.phys.ethz.ch

20 participants
28 discussions

error during install - alps 2.1.1
by Mateusz Łącki 29 Dec '12

29 Dec '12

Dear All, I am trying to install alps 2.1.1 - perhaps this will sove "Avoided problem" problem in my worm calculation. So far I haveproblems in setuping lapack. Installation of alps 2.0.2 took a week altogether to set up an modify the configfiles, but I have read that thenew version has updated installer so I suppose "old" tricks are just notappropriate. I wish to report I am stuck with: -- Using intel/mkl library: /opt/intel/composer_xe_2011_sp1.7.256/mkl CMake Error at config/FindLapack.… [View More]

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worm and Floating point exception
by Mateusz Łącki 21 Dec '12

21 Dec '12

Dear All I am using Worm to make some easy simulation with RESTRICT_MEASUREMENTS[N]=30 I understand that: If I set up the chemical potential correctly, then the MC algorithm encounters enough trajectories with N=30 and the output files contain resuls averagen only over trajectories with N=30 - approximation of the canonical ensemble. This is confirmed by user-experience and my weak recollecion of advide I have received here about oen year ago. But if I set the chemical potential wrongly … [View More]

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code for heisenberg model on fcc lattice
by sh po 17 Dec '12

17 Dec '12

Dear friends. I would appreciate if you could help me with using classic montecarlo simulation for fcc lattice on Heisenberg hamiltonian with s=1 and H=SIGMA Jij Si.Sj and Jij is just sum over nearest neibours.Would you mind telling me step by step that what should I do and exactly which codes I must use for this purpose?Its the first time I wanna use Alps and I dont know the steps of working with it. Many thanks for your helps. I would appreciate your immediate … [View More]

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Changing code in spinmc
by Kourosh Sartipi 17 Dec '12

17 Dec '12

Hi everyone. We wanted to change the code to do some more calculations for nearest neighbor in spinmc. So far I've tracked down the problem to the file alps/applications/mc/spins/localupdate.h. We've also added the edge type for nearest neighbour in xml file defining the unit lattice. The problem is that getting edge type for the graph always returns zero. Can you please help me find our how should we track down the problem? Getting the edge type would be like this: int edgeType = boost::… [View More]

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Worm algorithm and Green's function measurement
by Francisco Cordobés 16 Dec '12

16 Dec '12

Dear All, I have a question about the ALPS implementation of the Worm algorithm. In every paper I read about the Worm algorithm the same idea pervades: the Worm algorithm can easily sample Green's function(in imaginary time) because the movements of the worm do precisely that. Or in other words, Green's functions can be measured by histogramming the relative position of the head and tail of the worm(adding a 1 to the G(i-j,tau2-tau1) entry whenever the head is at i,tau2 and the tail is at j,… [View More]

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meaning of sweep and thermalization
by Sara Ghadiri 14 Dec '12

14 Dec '12

Dear friends Sorry I have 2 question: 1) Would you mind explaining me that what is exact meaning of "sweep" and "thermalization" and "update" in your classical montecarlo? 2) My other question is that , how can be sure that my system in my program will arrive to thermal equilibrium and after that the plot will be written?I mean what numbers should I choose for sweep or thermalization?

2 1

DMRG for 2D systems
by jessica.alfonsi＠unipd.it 14 Dec '12

14 Dec '12

Dear ALPS users and developers, is it possible to use the DMRG application in ALPS for two-dimensional systems (with not too many sites), like for instance two-leg ladder models, or is it necessary to implement additional the code ? Best regards, Jessica Alfonsi

2 1

DMRG slow convergence
by Emanuele Levi 12 Dec '12

12 Dec '12

Dear ALPS developers and users, I am using the DMRG algorithm to check the entropic properties of the ground state of an Heisenberg chain. More specifically in the region Jx=Jy=1 and Jz>1 , which is a gapped region. I sweep until I see that the entanglement entropy repeats on a certain pattern through next sweeps. At that stage the simulation should have converged on a good approximation of the ground state, and I take my data. For systems close to the critical point (e.g. Jz=1.001) the … [View More]

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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

2 1

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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Comp-phys-alps-users December 2012