November 2012 - 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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questions about wavefucntion
by 黄口口 01 Jan '13

01 Jan '13

Dear alps users: Now I am learning ALPS. It's useful for me. But I have question: How to get the wave function or some calculation about it, for example, 1.the participation ratio(=1 / \sum_i ｜< i | \psi > |^4 ) 2.calculation of entropy. I search in the mail group, some people face the same difficulty, but I cannot find the answer, can any of you provide me the solution? Thank you! Best wishes to you! xin 2012.11.08

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question about sparsediag
by 陈巧妮 01 Jan '13

01 Jan '13

Hi, everyone When I use sparsediag to diagnalize the Hamiltonian of Hubbard model, the paprameter is : CONSERVED_QUANTUMNUMBERS="Nup,Ndown" Nup_total=6 Ndown_total=6 the system size is L=12, no translation symmetry here, the process will take 100s, which is much slower than our own Davison code(It only take 20s). if I add the measurements MEASURE_ENERGY="True" MEASURE_LOCAL[density]=n MEASURE_LOCAL[double occupancy]=U*double_occupancy MEASURE_CORRELATIONS[density matrix_up]="cdag_up:c_up" MEASURE_CORRELATIONS[density matrix_down]="cdag_down:c_down" the process will take 900s. Does anyone know how to speed up this calculation? Or at least avoid the waste time on the measurements -- Qiaoni Chen Department of Chemistry, Princeton University Princeton, NJ, 08544 Tel +1-609-865-0817

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4 point correlations
by "Michał Maik" 31 Dec '12

31 Dec '12

Hi, I was wondering if there was a way to calculate any 4 point correlation functions. I am interested in calculating: <a_dag(i) a_dag(i) a(j) a(j)> I would like to look at pair superfliudity and these correlation functions would be very useful. As a side question, is there a way to use the winding numbers from the worms code output to study this effect? Thank you. Best Michal Maik

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Fwd: string order parameter in ALPS
by Synge Todo 31 Dec '12

31 Dec '12

Dear ALPS Developers, Can anyone tell him how to measure the string order parameter in the ALPS exact diagonalization code, or in the ALPS DMRG code? Best, Synge Begin forwarded message: > 差出人（再送）: wistaria(a)ap.t.u-tokyo.ac.jp > 差出人: hamid mosadegh <hamid.mosadegh(a)gmail.com> > 件名: Re: string order parameter in ALPS > 日時: 2012年11月27日 14:30:20 JST > 宛先: Synge Todo <wistaria(a)comp-phys.org> > > Dear Professor Todo > > Do you know any codes or libraries to evaluate string order for fermion Hubbard. > If there is any code, I think i must write it myself. > Is it possible to access to eigenvectors calculated using ALPS. > If I have these eigenvectors, i can evaluate string order. > > Thanks for attentions and good answers.

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question about ALPS
by hamid 31 Dec '12

31 Dec '12

Dear ALPS user is it possible to define a distance dependent terms to Hamiltonians ,like this term, V/|i-j| I try to define this term but the program can not evaluate i & j. thanks in advance

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Local observables in quantum montecarlo
by Francisco Cordobés 29 Nov '12

29 Nov '12

Dear all, I am trying to understand how to use the qmc codes from ALPS to get some local observables from lattice models. If I understand it correctly, the way qmc codes work is in imaginary time and in that representation one can measure thermodynamic quantities. In the case of dynamical quantities(by this I mean dynamical susceptibilities), the results in imaginary time have to be analytically continued back to the real time axis and then evaluated. This is done usually, from what I gather from the literature, using maximum entropy methods. I have read through the tutorials on the alps website and the different slides by the ALPS creators that I found on google and I haven't found any example of the last type of calculations. Neither how to "tell" ALPS to measure a non-averaged susceptibility or how to analytically continue it to the real axis. Is it possible with ALPS as it is or do I need to write my own c++ code, based on ALPS, to access that kind of information? If it is possible, could someone tell me where I can find documentation on how to do it specifically with ALPS? Kind regards, Paco Cordobes

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Fwd: honeycomb bilayer
by mojtaba alaei 29 Nov '12

29 Nov '12

Dear All Recently I tried to reproduce the result of a paper about two honeycomb bilayer (PRB.85.184412 <http://prb.aps.org/forward/PRB/v85/i18/e184412>) . The paper used simple MC simulations ( in fact authors used exchange MC technique <http://dx.doi.org/10.1143/JPSJ.65.1604>) with classical Heisenberg model to derive susceptibility of this system. Authors used three different exchange parameters: 1-J1 as NN interaction in honeycomb surfaces 2-J2 as NNN interactions in honeycomb surfaces 3-Jc as face-to face intra-bilayer interactions. I used exactly the same parameters of the paper (I use minus sign for exchange). My setup is as follows: ****************************************** ****************************************** Exchange parameters setting: J1=30.2 K, J2/J1=0.1 and Jc/J1=0.1. Landee g-factor: g=2 steps for thermalization: 50000 steps for sampling: 1000000 lattice size: L=24 ****************************************** ****************************************** All of my parameters are the same as the paper except that I used more steps for sampling and for thermalization because the system is frustrated. The following plots are mine and from the paper ( I derived the data of fig(8,c) of the paper by using G3DATA): The ALPS result (mine) [image: Inline image 1] The PRB.85.184412 result (please see fig 8_c of the paper): [image: Inline image 2] *As you can see the plot of mine has a maximum around 40 K while the plot of PRB.85.184412 has a maximum around 60-70 K and also the plot shows a minimum around 20 K. W**hat do you think? what is my fault? Is it a bug or something else?* If somebody like to repeat the calculation, these are my input files: the python script: #================================= import pyalps import matplotlib.pyplot as plt import pyalps.plot #prepare the input parameters parms = [] for t in [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 43, 46, 49, 52, 55, 58, 61, 64, 67, 70, 75, 80, 85, 90, 95, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, 380, 390, 400 ]: parms.append( { 'LATTICE_LIBRARY' : "graphene_bilayer.xml", 'LATTICE' : "graphene bilayer lattice", 'S' : 1.5, 'T' : t, 'J1' : -30.2, 'J2' : -3.02, 'J3' : -3.02, 'g' : 2.00, 'THERMALIZATION' : 50000, 'SWEEPS' : 1000000, 'UPDATE' : "local", 'MODEL' : "Heisenberg", 'L' : 24 } ) #write the input file and run the simulation input_file = pyalps.writeInputFiles('parm2b',parms) pyalps.runApplication('spinmc',input_file,Tmin=300, MPI=4, mpirun='mpirun') #get the list of result files result_files = pyalps.getResultFiles(prefix='parm2b') print "Loading results from the files: ", result_files #print the observables stored in those files: print "The files contain the following mesurements:", print pyalps.loadObservableList(result_files) #load a selection of measurements: data = pyalps.loadMeasurements(result_files,['Susceptibility']) #make a plot for the magnetization: collect Magnetziation as function of T plotdata = pyalps.collectXY(data,'T','Susceptibility') # convert the data to text file for plotting using another tool print "The results in plain text are:" print pyalps.plot.convertToText(plotdata) print "Saving into file parm2b.txt" f = open ('parm2b.txt','w') f.write(pyalps.plot.convertToText(plotdata)) f.close() #================================ the lattice file (xml format) ===================================== <LATTICES> <LATTICE name="hexagonal lattice" dimension="3"> <PARAMETER name="a" default="1"/> <PARAMETER name="c" default="1"/> <BASIS> <VECTOR>a 0 0</VECTOR> <VECTOR>a/2 a*sqrt(3)/2 0</VECTOR> <VECTOR>0 0 c</VECTOR> </BASIS> <RECIPROCALBASIS> <VECTOR>2*pi/a -2*pi/a/sqrt(3) 0 </VECTOR> <VECTOR>0 4*pi/a/sqrt(3) 0 </VECTOR> <VECTOR>0 0 2*pi/c</VECTOR> </RECIPROCALBASIS> </LATTICE> <UNITCELL name="graphene bilayer" dimension="3" vertices="4"> <VERTEX><COORDINATE> 0.000000000000 0.0000000000 0 </COORDINATE></VERTEX> <VERTEX><COORDINATE> 0.333333333333 0.3333333333 0</COORDINATE></VERTEX> <VERTEX><COORDINATE> 0.000000000000 0.0000000000 0.5 </COORDINATE></VERTEX> <VERTEX><COORDINATE> 0.333333333333 0.3333333333 0.5</COORDINATE></VERTEX> <EDGE type="1"><SOURCE vertex="1"/><TARGET vertex="2" offset=" 0 0 0"/></EDGE> <EDGE type="1"><SOURCE vertex="3"/><TARGET vertex="4" offset=" 0 0 0"/></EDGE> <EDGE type="1"><SOURCE vertex="2"/><TARGET vertex="1" offset=" 1 0 0"/></EDGE> <EDGE type="1"><SOURCE vertex="2"/><TARGET vertex="1" offset=" 0 1 0"/></EDGE> <EDGE type="1"><SOURCE vertex="4"/><TARGET vertex="3" offset=" 1 0 0"/></EDGE> <EDGE type="1"><SOURCE vertex="4"/><TARGET vertex="3" offset=" 0 1 0"/></EDGE> <EDGE type="2"><SOURCE vertex="1"/><TARGET vertex="3" offset=" 0 0 0"/></EDGE> <EDGE type="2"><SOURCE vertex="2"/><TARGET vertex="4" offset=" 0 0 0"/></EDGE> <EDGE type="3"><SOURCE vertex="1"/><TARGET vertex="1" offset=" 1 0 0"/></EDGE> <EDGE type="3"><SOURCE vertex="1"/><TARGET vertex="1" offset=" 0 1 0"/></EDGE> <EDGE type="3"><SOURCE vertex="1"/><TARGET vertex="1" offset=" 1 -1 0"/></EDGE> <EDGE type="3"><SOURCE vertex="2"/><TARGET vertex="2" offset=" 1 0 0"/></EDGE> <EDGE type="3"><SOURCE vertex="2"/><TARGET vertex="2" offset=" 0 1 0"/></EDGE> <EDGE type="3"><SOURCE vertex="2"/><TARGET vertex="2" offset=" 1 -1 0"/></EDGE> <EDGE type="3"><SOURCE vertex="3"/><TARGET vertex="3" offset=" 1 0 0"/></EDGE> <EDGE type="3"><SOURCE vertex="3"/><TARGET vertex="3" offset=" 0 1 0"/></EDGE> <EDGE type="3"><SOURCE vertex="3"/><TARGET vertex="3" offset=" 1 -1 0"/></EDGE> <EDGE type="3"><SOURCE vertex="4"/><TARGET vertex="4" offset=" 1 0 0"/></EDGE> <EDGE type="3"><SOURCE vertex="4"/><TARGET vertex="4" offset=" 0 1 0"/></EDGE> <EDGE type="3"><SOURCE vertex="4"/><TARGET vertex="4" offset=" 1 -1 0"/></EDGE> </UNITCELL> <LATTICEGRAPH name = "graphene bilayer lattice"> <FINITELATTICE> <LATTICE ref="hexagonal lattice"/> <PARAMETER name="W" default="L"/> <PARAMETER name="H" default="1"/> <EXTENT dimension="1" size="L"/> <EXTENT dimension="2" size="W"/> <EXTENT dimension="3" size="H"/> <BOUNDARY type="periodic"/> </FINITELATTICE> <UNITCELL ref="graphene bilayer"/> </LATTICEGRAPH> </LATTICES> ======================================================================= Thanks in advanced Mojtaba Alaei

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non-next-neighbor Hamiltonians
by Emanuele Levi 27 Nov '12

27 Nov '12

Dear ALPS developers, does ALPS ( and in particular the DMRG solver) support spin Hamiltonians with non-next interacting terms, e.g. Sz(i)Sz(i+3)? Many thanks. Kindest regards. -- Emanuele Levi emanuele.levi(a)gmail.com

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Resuming a DMRG simulation
by A. Giovanni Ramirez Garcia 23 Nov '12

23 Nov '12

Dear All, I'm using the DMRG code in the alps-2.1.0d1-r6050 version and I would like to resume some simulations after they have finish properly. I want to increase the number of sweeps previously defined (sometimes from 3 to 4) then when it finishes I just add the parameters to my python script to start from the sweep 3. When I ran the script it stops due an error of *.dat files not found. Where ALPS save the *.dat files to resume from another simulation? I tried to find them by myself without success. Should I give another parameter to let ALPS knows I want to save that files? Giovanni Ramirez-Garcia

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