November 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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Exact Diagonalization Fermion Hubbard
by Sriluckshmy Viswanathan 12 Dec '14

12 Dec '14

Dear all, I am trying to solve the fermion hubbard model on a square lattice with a small cluster size of 2x2 using exact diagonalization. I want to look at the energy levels at half filling. I used to N_total parameter to fix the filling, but the energy levels results dont change if I change this parameter. Could you please help me with this problem? I have attached the param file that I used. I am using fulldiag of ALPS. Regards Sriluckshmy

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bug in mps_optim
by Dominique Delande 30 Nov '14

30 Nov '14

Dear all, I think that there is a bug in how mps_optim changes the bond dimension during successive sweeps. In the alps-2.2.b3-r7462-src/alps/applications/dmrg/mps/mps_optim/run_sim.cpp file, line 64 reads: double step = (int(parms["MAXSTATES"]) - init_bond) / (parms["nsweeps"]-1); It is supposed to compute the increment of the bond size at each step (starting from init_bond at the first sweep, reaching MAXSTATES at the final sweep). How, the division if performed using integers before being written to the variable step as a double. For example, if (int(parms["MAXSTATES"]) - init_bond) < (parms["nsweeps"]-1), step will be 0.0, presumably not the intended value. A simple fix is to perform the division using double, something like: double step = ((double)(int(parms["MAXSTATES"]) - init_bond)) / (parms["nsweeps"]-1); Best regards Dominique Delande -- Dominique Delande (Dominique.Delande(a)lkb.upmc.fr) Laboratoire Kastler-Brossel - Case 74 - Universite P. et M. Curie 4, place Jussieu, F-75252 Paris Cedex 05, FRANCE Phone : +33 1 44 27 27 97 - Fax : +33 1 44 27 38 45 Acces : Tour 13, Couloir 12-13, 3eme etage - Bureau 316

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Re: [ALPS-users] Results is different for worm(sse) and wolfram mathematica
by vitbka konef 25 Nov '14

25 Nov '14

My name is Konev Vitaliy. 1) Yes , it does. 2) In Mathematica I use the periodic boundary conditions. How realised the periodic boundary conditions in ALPS library? I was attached test of the result for periodic boundary condition.

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Results is different for worm(sse) and wolfram mathematica
by vitbka konef 22 Nov '14

22 Nov '14

First , I was obtained density of magnetization and density of energy curves of isotropic Heisenberg model on square lattice (2x2) using worm and dirloop_sse. After I was obtained these curves with wolfram mathematica. Curves for magnetization density(density of energy) obtained with mathematica and worm(sse) is strongly differ one from another.They must match. I was attached the files of mathematica and Heis2x2.py.

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total acceptance rate
by tesfaye mamuye 20 Nov '14

20 Nov '14

Dear ALPS developers and users I'm using CT-HYB impurity solver for single site DMFT problem. While i was simulating single site single-orbital dmft problem using CT-HYB the value of total acceptance rate negative. Is this negative value of total acceptance rate possibly accepted ?what is this negative value of total acceptance rate mean ? Tesfaye MamuyeAddis Ababa University, Ethiopia

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Anisotropic XY model in transverse magnetic field
by Олеся Крупніцька 17 Nov '14

17 Nov '14

Dear ALPS team, I want to inform you that I have found my mistake in extracting results for magnetization of anisotropic XY model on frustrated diamond spin chain in transverse magnetic field. Best regards, Olesia Krupnitska

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Anisotropic XY model in transverse magnetic field
by Олеся Крупніцька 13 Nov '14

13 Nov '14

Dear ALPS team, I am trying to obtain magnetization curve of anisotropic XY model on frustrated diamond spin chain in transverse magnetic field (m^x) using full diagonalization. For this purpose I have prepared such input file for delta=1.5; LATTICE="lattice_diamond" MODEL="spin" LATTICE_LIBRARY="lattice-diamond.xml" local_S=1/2 Jxy1 = 0.85 Jxy2 = 3.0 Jxy3 = 1.15 Jz1 = 1.275 Jz2 = 4.5 Jz3 = 1.725 L = 2 T = 0.001 {Gamma =4;} {Gamma =4.05;} {Gamma =4.1;} {Gamma =4.15;} {Gamma =4.2;} {Gamma =4.25;} {Gamma =4.3;} {Gamma =4.35;} {Gamma =4.4;} {Gamma =4.45;} {Gamma =4.5;} {Gamma =4.55;} {Gamma =4.6;} {Gamma =4.65;} {Gamma =4.7;} {Gamma =4.75;} {Gamma =4.8;} {Gamma =4.85;} {Gamma =4.9;} {Gamma =4.95;} {Gamma =5;} {Gamma =5.05;} {Gamma =5.1;} {Gamma =5.15;} {Gamma =5.2;} {Gamma =5.25;} {Gamma =5.3;} {Gamma =5.35;} {Gamma =5.4;} {Gamma =5.45;} {Gamma =5.5;} {Gamma =5.55;} {Gamma =5.6;} {Gamma =5.65;} {Gamma =5.7;} {Gamma =5.75;} {Gamma =5.8;} {Gamma =5.85;} {Gamma =5.9;} {Gamma =5.95;} {Gamma =6;} lattice-diamond.xml is: <LATTICES> <LATTICEGRAPH name="lattice_diamond"> <FINITELATTICE> <LATTICE dimension="1"> <BASIS> <VECTOR>1</VECTOR> </BASIS> </LATTICE> <PARAMETER name="L"/> <EXTENT size="L"/> <BOUNDARY type="periodic"/> </FINITELATTICE> <UNITCELL dimension="1" vertices="3"> <VERTEX id="1" type="0"> </VERTEX> <VERTEX id="2" type="0"> </VERTEX> <VERTEX id="3" type="0"> </VERTEX> <EDGE type="2"> <SOURCE vertex="1"/> <TARGET vertex="2"/> </EDGE> <EDGE type="3"> <SOURCE vertex="1"/> <TARGET vertex="3"/> </EDGE> <EDGE type="1"> <SOURCE vertex="2"/> <TARGET vertex="3"/> </EDGE> <EDGE type="3"> <SOURCE vertex="3"/> <TARGET vertex="2" offset="1"/> </EDGE> <EDGE type="1"> <SOURCE vertex="3"/> <TARGET vertex="1" offset="1"/> </EDGE> </UNITCELL> </LATTICEGRAPH> </LATTICES> It works perfect for L=2 (6 sites), but I cant obtain correct magnetization curve for L=3 (9 sites) or L= 4 (12 sites) etc. Would you be so kind to explain me why it works well for small chain and worse for slightly larger chain? Best regards, Olesia Krupnitska

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correlation function and alternating chain
by Jalal Jahangiri 01 Nov '14

01 Nov '14

Hello Dear ALPs users I have 2 questions.I am novice in ALPS. 1- I want to calculate correlation function for coupled ladders. my input file is attached in the output file, there are 4 values of correlation function for nearest neighbors. this is part of output file *Spin Correlations*[( 0,0 ) -- ( 0,1 )]*Spin Correlations*[( 0,0 ) -- ( 0,1 )]*Spin Correlations*[( 0,0 ) -- ( 0,1 )]*Spin Correlations*[( 0,0 ) -- ( 0,1 )] -whereas i expect there is one of them or at least 3 of them (x-y-z), is there a bug in the input file or something else? 2- How do I define an alternating chain? (my mean is alternating coupling constants) Best Regards

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