June 2014 - Comp-phys-alps-users

Inconsistent comment in generate_spline_matrix in the DMFT folder
by Kuangshing Chen 22 Jul '15

22 Jul '15

Hi, The function generate_spline_matrix in fouriertransform.C in the dmft folder shows the comments as follows: // A is the matrix whose inverse defines spline_matrix // // 6 6 // 1 4 1 // 1 4 1 // A = ... // // 1 4 1 // -2 0 0 2 However, the following codes, dense_matrix A = 4*dt/6.*boost::numeric::ublas::identity_matrix<double>(Np1); for (int i=1; i<Np1-1; i++) { A(i,i-1) = dt/6.; A(i,i+1) = dt/6.; } A(0,0) = 1.; A(0, Np1-1) = 1.; A(Np1-1, 0) = -2.*dt/6.; A(Np1-1, 1) = -1.*dt/6.; A(Np1-1, Np1-2) = 1*dt/6.; A(Np1-1, Np1-1) = 2*dt/6.; the red lines will make the matrix looks like // 6 6 // 1 4 1 // 1 4 1 // A = ... // // 1 4 1 // -2 *-1* *1* 2 Is the comment correct or the code correct? Any reference for this algorithm? Thank you, Kuang-Shing Chen

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Help regarding sparse diagonalization
by Sriluckshmy Viswanathan 15 Aug '14

15 Aug '14

Hi, I am writing a code for the computing gap in kitaev-heisenberg model on the honeycomb lattice using sparse diagonalization. When the coupling for the kitaev term is zero the model patch that I wrote should match the model that is inbuilt. But that doesnt happen. I may have made a mistake in the model patch which is as follows. <HAMILTONIAN name="kitaev heisenberg"> <PARAMETER name="J" default="1"/> <PARAMETER name="Jz" default="0"/> <PARAMETER name="Jx" default="0"/> <PARAMETER name="Jy" default="0"/> <BASIS ref="spin"/> <BONDTERM source = "i" target="j"> J*Sz(i)*Sz(j) +J*exchange_xy(i,j) </BONDTERM> <BONDTERM type="0" source="i" target="j"> Jz*Sz(i)*Sz(j) + J*Sz(i)*Sz(j) +J*exchange_xy(i,j) </BONDTERM> <BONDTERM type="1" source="i" target="j"> Jx*Sx(i)*Sx(j) + J*Sz(i)*Sz(j) +J*exchange_xy(i,j) </BONDTERM> <BONDTERM type="2" source="i" target="j"> Jy*Sy(i)*Sy(j) + J*Sz(i)*Sz(j) +J*exchange_xy(i,j) </BONDTERM> </HAMILTONIAN> I have also attached the output that I got in dat format. Could you please help me with this problem? Sriluckshmy

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Alps Installation error
by Soumen Bag 21 Jun '14

21 Jun '14

Hi experts, I have installed alps. Some test were failed. After installation I am getting following error. [soumen@Rahman ALPS_INSTALL_PACKAGES]$ alpspython Python 2.7 (r27:82500, May 26 2014, 22:54:42) [GCC 4.1.2 20080704 (Red Hat 4.1.2-48)] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> import pyalps.cthyb >>> import pyalps.mpi PMGR_COLLECTIVE ERROR: unitialized MPI task: Missing required environment variable: MPIRUN_RANK Can anyone suggest where things are going wrong? Any help will be strongly appreciated. Thanks, *Soumen Kumar Bag* *Physical Science Dept.* *IISC*

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Full exact diagonalization, all eigenvalues and eigenvectors
by Vladimir Iglovikov 19 Jun '14

19 Jun '14

Dear all, I understand how to do exact diagonalization and obtain, say, energy vs temperature plot using python. function /pyalps.evaluateFulldiag//VersusT/ works really well But right now I want to do exact diagonalization and get all eigenvalues and corresponding eigenstates and I can not figure out which function should I use. best regards, Vladimir

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Exact Diagonalization: Heisenberg Hamiltonian, Boundary Conditions
by Daniel Guterding 18 Jun '14

18 Jun '14

Dear ALPS users, I am trying to use the sparsediag application to solve the standard Heisenberg Hamiltonian for various geometries. So far I could however not figure out which Hamiltonian is actually implemented in the model "spin". Is it J*S1*S2, 2J*S1*S2 or 0.5J*S1*S2 ? Generally it would be good to know where in the code the model Hamiltonians can be found. My second question is about boundary conditions. First I tried the "chain lattice" and varied the boundary conditions with the keyword "boundary" set to "open" or "closed" respectively, which had no effect on the determined eigenvalues. Is there a difference between using "open chain lattice" and "chain lattice" with "boundary" set to "open" ? I presume the reason for my problems is a simple user error, hence some help would be appreciated. Best regards, Daniel

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(no subject)
by ANIRBAN DUTTA 18 Jun '14

18 Jun '14

Hi, I have installed alps2.2 in my desktop with os fedora 19. It has passed all the tests when I run "make test" and "make install" Now to test the installation I have copied the alps tutorial code-02-c++ solution to a new directory and run "make". It has returned an executable ising but when I run that executable it failed and returned ./ising: error while loading shared libraries: libalps.so.2: cannot open shared object file: No such file or directory Can anybody please tell me what I have to change to make it run ? Thanks, -- ANIRBAN DUTTA IACS INDIA

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Sparse Diagonalization
by Sriluckshmy Viswanathan 18 Jun '14

18 Jun '14

Hi, I had a query regarding sparse diagonalization in ALPS. The system that I am working with is heisenberg model on honeycomb lattice with pbc. I have taken 3 x 3 units which amounts to 12 lattice sites. I did a brute force diagonalization using matlab and a sparsediag of ALPS and am comparing the results. In matlab if I just look at the low lying energy i get 1 ground state 3 first excited states and 5 second excited states with gap of 2.27 and 4.61 between them respectively. Using ALPS sparsediag i get in the k = [0,0], i get an eigenvalue -6.75 and in the other momentum sectors an eigenvalue -5.75 where the energy gap is printed to be 1. My main concern is why aren't the two results matching qualitatively. I understand that one shouldn't compare the exact numbers but the "degeneracy" property should be the same i am guessing. The eigenvalue that is printed is the ground state energy of that momentum sector. Is this correct? If this is then the energy gap which is being measured from the difference in the ground state energy of the two low lying sectors seems incorrect right. Because the energy gap should be measured after sorting the eigenvalues of all the sectors and then measured isnt it. Could this be the reason why the results are not matching? Is there a way to get qualitatively get results that I get with Matlab? I tried fulldiag of this system and got a std::bad_alloc which i am guessing that its because of memory. Is there a way to handle this? Any help will be appreciated. Thanks and Regards Sriluckshmy

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Re: [ALPS-users] alternative fermion Hubbard (Fernando Iemini)
by Fernando Iemini 16 Jun '14

16 Jun '14

dear all, thanks for the responses, and sorry for the delay to reply. Yes, i was using the dmrg, and in fact using this new dmrg application `mps_optim`, as suggested by Michele Dolfi, solved my problem! I didn't know about this application, is there somewhere i can find a tutorial about it, or is it exactly the same input's as dmrg? And just a last point, in this application can i measure some "four-point" correlations, like "cdag_m:c_{m+1}:cdag_n:c_{n+1}" ? best regards, Fernando. ----------------------------------- Date: Thu, 12 Jun 2014 08:52:52 +0200 From: Michele Dolfi <dolfim(a)phys.ethz.ch> To: comp-phys-alps-users(a)lists.phys.ethz.ch Subject: Re: [ALPS-users] alternative fermion Hubbard Message-ID: <52E3FD2A-60E3-4D48-8315-1ACDF7348498(a)phys.ethz.ch> Content-Type: text/plain; charset="us-ascii" Hi Fernando, If you are using a recent version of ALPS, e.g. 2.2.0b3, you can use the new dmrg application `mps_optim`. It works the same way as the `dmrg` application, but additionally allows you to measure correlation functions for i<j, which very often is good enough. MEASURE_HALF_CORRELATIONS[ cdag_up c_up]="cdag_up:c_up" Best regards, Michele -- ETH Zurich Michele Dolfi Institute for Theoretical Physics HIT G 32.4 Wolfgang-Pauli-Str. 27 8093 Zurich Switzerland dolfim(a)phys.ethz.ch www.itp.phys.ethz.ch +41 44 633 78 56 phone +41 44 633 11 15 fax On Jun 12, 2014, at 2:08 AM, Ryo IGARASHI <rigarash(a)issp.u-tokyo.ac.jp> wrote: > Hi, Fernando, > > Assuming that you use DMRG simulation since you specify 'MAXSTATES'. > > > (2014/06/12 0:10), Fernando Iemini wrote: >> I've using the ''alternative fermion Hubbard'' model, with open boundary >> conditions, and analyzing its single-particle correlations, <cdag_up:c_up>. >> I'm not being able however to compute these observables for larger >> lattices, e.g., L=~160. I'm getting a "segmentation fault" message, does >> anybody know why is happening this error, maybe due to memory? If so, what >> would be good parameters in order to avoid it? >> >> Here is the script i'm using: >> >> LATTICE="open chain lattice" >> MODEL="alternative fermion Hubbard" >> CONSERVED_QUANTUMNUMBERS="N,Sz,Nup,Ndown" >> N_total=160 >> Sz_total=0 >> Nup_total=80 >> Ndown_total=80 >> mu=0 >> t=1 >> NUMBER_EIGENVALUES=1 >> L=160 >> MAXSTATES=100 >> MEASURE_CORRELATIONS[cdag_up c_up]="cdag_up:c_up" >> {U = 9.000000e-01,V=5.500000e-01,TRUNCATION_ERROR=1e-7} > > This is memory issue. The problem is that 'MEASURE_CORRELATIONS' > collects all pair sites. Observing ~10000 measurements costs too much > memory. > > Not tested, but I believe that you can avoid this issue by tweaking > models.xml and lattices.xml. Change the name of some specific operator > and just calculating between them. > > -- > Ryo IGARASHI, Ph.D. > rigarash(a)issp.u-tokyo.ac.jp > tel: 04-7136-5343, fax: 04-7136-3441 > OpenPGP fingerprint: BAD9 71E3 28F3 8952 5640 6A53 EC79 A280 6A19 2319 >

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PROBLEM WITH INSTALLATION OF ALPS
by emmanuel enukpere 16 Jun '14

16 Jun '14

I am trying to install and test alps on Ubuntu 12.04 32-bit system. Things went pretty fine until it got the point where it wanted to install the project , then it reported that “file cannot create directory /opt/alps/include. Maybe need administrative privileges. ” What should I do? Please help as I do not know how to proceed. Details of the last few steps before the error warning are shown below: [ 99%] Built target accumulate_if [ 99%] Built target vector_functions [100%] Built target vector_valarray_conversion Install the project... -- Install configuration: "Release" CMake Error at cmake_install.cmake:36 (FILE): file cannot create directory: /opt/alps/include. Maybe need administrative privileges. make: *** [install] Error 1 enukpere@ubuntu:~/alps-2.1.1-r6176-src-with-boost/build$ sudo cmake_install.cmake [sudo] password for enukpere: sudo: cmake_install.cmake: command not found Enukpere,E.E. Physics Department, University of Benin, Benin City, Nigeria.

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Alps Maximum Entropy Method
by Soumen Bag 16 Jun '14

16 Jun '14

Hi! I am using Alps library for my project. I need to use MEM of alps. But i did not find any tutorial for this. Can anyone please let me how to use ALPS's MEM? Thanks, *Soumen Kumar Bag* *Physical Science Dept.* *IISC*

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