December 2012 - Comp-phys-alps-users

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.cmake:43 (STRING): string sub-command REGEX, mode REPLACE needs at least 6 arguments total to command. Call Stack (most recent call first): CMakeLists.txt:304 (find_package) This is FindLapack.cmake: 39 IF($ENV{MKL} MATCHES "mkl") 40 MESSAGE(STATUS "Using intel/mkl library: $ENV{MKL}") 41 #look for the path where the mkl is installed 42 STRING(REGEX MATCHALL "[-][L]([^ ;])+" MKL_PATH_WITH_PREFIX "$ENV{MKL}") 43 STRING(REGEX REPLACE "[-][L]" "" MKL_PATHS ${MKL_PATH_WITH_PREFIX}) 44 ENDIF($ENV{MKL} MATCHES "mkl") "CMakeLists.txt:304" is a bigger mystery as there are plenty of those files, butonly two of them contain line 304: *********** ./alps/CMakeLists.txt ********* 300 301 # Lapack 302 if (NOT ALPS_FOR_VISTRAILS) 303 if (NOT LAPACK_FOUND) 304 find_package(Lapack) 305 endif (NOT LAPACK_FOUND) 306 if (LAPACK_FOUND) 307 set(ALPS_HAVE_LAPACK 1) 308 set(ALPS_HAVE_BLAS 1) 309 endif(LAPACK_FOUND) *********** ./alps/src/boost/CMakeLists.txt ********* 300 set_target_properties(boost PROPERTIES COMPILE_DEFINITIONS BOOST_THREAD_BUILD_LIB=1) 301 endif(BUILD_SHARED_LIBS) 302 endif(WIN32) 303 304 if (NOT ALPS_BUILD_SOURCE) 305 if(MSVC) 306 get_target_property(LIB_NAME ${ALPS_BOOST_LIBRARY_NAME} LOCATION) 307 add_custom_command(TARGET ${ALPS_BOOST_LIBRARY_NAME} POST_BUILD 308 COMMAND ${CMAKE_COMMAND} -E copy ${LIB_NAME} ${PROJECT_BINARY_DIR}/bin) 309 endif(MSVC) Somehow i feel that the first one is the right one. My envs: lacki@mieczyslaw:~/alps-2.1.1-r6176-src $ echo $MKL /opt/intel/composer_xe_2011_sp1.7.256/mkl Regards, Mateusz Łącki

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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 then the average number of particles from the Grand canonical point of view is for example 45, and there are not enough (maybe even 0) trajectories to sample with N=30. In this case the output files contain somethink that makes the following python "result getter": ********************** get.py *********************** import pyalps import sys rf=pyalps.getResultFiles(prefix=sys.argv[1]) data = pyalps.loadMeasurements(rf) obl=pyalps.loadObservableList(rf) ******************************************************* behave rude: it says Floating point exception. and quits (even if only one of let say 500 output files is corrupt). Of course adjusting the chemical pontential is the key, but this seems to be complicated in a case where the phase diagram is complicated (I would have to do some form of extrapolation or binary search to get the right mu). On the other hand I see no other way to solve it. Another way to deal with that is to generate input files containing only one set of input parameters - this way each datapoint has its own prefix. It is not complicated, but somehow contrary to the idea behind the current format of the input data. Morover it is likely to make a bookkeeping mess. I have two questions: 1. is there a way to read these "faulty", "undersampled" ouput files without "Floating point exception." (I could then set up calculations for let say 10 different values of mu an choose mu that gave the closes answer - the simplest to code). 2. is there some easy way to make the MC autoadjust the chemical potential ? Regards, Mateusz Lacki

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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 attention to this matter.

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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::get(alps::edge_type_t(), graph, *iter); // iter is out_edge_iterator but the return value is always zero. (executing the exact same code for when the library parses the xml file produces the correct results. namely in file alps/src/alps/lattice/unitcell.c) Yours, Kourosh

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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,tau1). The current version of the ALPS Worm code(alps 2.1) does not measure Green's functions and the issue was discussed, albeit briefly, earlier this year in a couple of e-mails, and it was mentioned that it would actually be too costly computationally to get all the N^2 values and only the relative distances would be measured. Is it because of the computational time needed in the Green's function configuration space would be too long and the current implementation samples mostly the partition function configuration space(by shifting/moving closed loops)? Or is it due to some technical detail that is usually not mentioned in the papers?(or that I might have not understood it correctly). Cheers, Francisco Cordobes

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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?

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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

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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 results I get are comparable to exact results, and everything works perfectly. When I increase the gap though, I manage to get sensible results only on very short chains. To explain you what happens on longer chains I am attaching to this mail a plot of the entropy against the iterations. This picture refers to Jx=Jy=1 Jz=2.5 L=42 Nstates=400 Nsweeps=40 periodic boundary conditions As you can see it struggles to converge to a sensible value. This picture isa goodrepresentative of any simulation I run. There are two features I see: 1- jumps from a lower value to an higher one: I think this could be explained with the fact that as the system sweeps, it gets short range correlations and it converges immediately to another ground state. 2- the slow convergence in the final stage to a sensible value. This I really don't know how to explain. Do you know what is going on, and how could I enhance the simulation? Just increasing the number of sweeps or there is a smarter way in your opinion? (It looks like increasing the states kept doesn't change too much the situation, and I really need periodic boundaries for the kind of plot I want to produce). Many thanks again for your precious help. Kindest regards. -- Emanuele Levi emanuele.levi(a)gmail.com

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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

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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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