April 2013 - 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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Units of susceptibility from ALPS
by Zlata Pchelkina 23 Apr '13

23 Apr '13

Dear users, can you please help me to understand in that units I get the susceptibility in ALPS and how to transform it in common emu/mol or cm-3/mol? If I plot the susceptibility for the chain, it is quite easy - on the Y axis I've got |J|*chi/g^2*mu_B^2*N, N - number of spins in the chain. But if I have 3D lattice, what is the N in this case? As far as I understand, it is not just number of unit cells. Thank you for your cooperation.

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Running ALPS worm/dir_loop in a cluster
by Francisco Cordobés 02 Apr '13

02 Apr '13

Hi to all, I am planning on running some large 2D Bosons simulations with ALPS in a cluster. Specifically I will we using the worm algorithm(and dir_loop for some checks). The cluster I am running my simulations in uses a PBS queuing system. All the tutorials and examples I have seen online are for single machine or assuming one doesn't have to use a queuing system. Is there any PBS functionality implemented in pyalps? Also, and this is a practical question, for running large simulations with ALPS, I understand from the examples and documentation that the best way to do it is to set a very large number of sweep steps and then run it for a fixed time. After that time check if the measurements I am interested in have converged and if not, run it for a bit longer. Is that the best option or is there a better way of doing it? Thanks in advance, Francisco Cordobes

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What am I doing wrong?
by Jakub Zakrzewski 01 Apr '13

01 Apr '13

Hello everybody, Let us take such a simple input file with irrelevant name parbh: LATTICE="open chain lattice" MODEL="boson Hubbard" L=8 Nmax=4 N_total=8 NONLOCAL=0 U = 1.0 t = 0.24 CONSERVED_QUANTUMNUMBERS="N_total" SWEEPS=8 NUMBER_EIGENVALUES=1 {MAXSTATES=100} I produce parbh.in.xml and then I run sparsediag getting a proper ground state energy (checked independently outside alps) -1.457060131536948 I use DMRG on the same input file obtaining LOWER eigenenergy... -1.6132399980266807 the result is little dependent on SWEEPS. MAXSTATES (which are rather large) and is obviously incorrect. I must be doing something wrong but what is it? Help welcome Thanks in advance, kuba -- Jakub Zakrzewski Zakład Optyki Atomowej Instytut Fizyki im. M. Smoluchowskiego ul. Reymonta 4, 30-059 Kraków, Poland +48-12-6635555, fax +48126338494 http://chaos.if.uj.edu.pl/~kuba

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eigenvectors of ED
by Bo-Nan JIANG 01 Apr '13

01 Apr '13

Hi, all I find in the ALPS tutorials of ED that "The output file now contains all the eigenvectors ". What does it mean? Does it mean that I could know all eigenvectors with respect to the corresponding eigenvalues? If it is ture, then what is the basis of eigenvectors? And how can I access to the eigenvectors ('cause I find none in the output xml files)? Bo-Nan -- Stay foolish,Stay hungry.

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