October 2009 - Comp-phys-alps-users

Problems with worms??
by Jakub Zakrzewski 27 Oct '10

27 Oct '10

Hello, Sometimes QMC worm code (used on Bose-Hubbard) terminates with the following error: here come first earlier succesful simulations then ... Created run 85 remote on Host ID: 84 Created run 86 remote on Host ID: 85 Created run 87 remote on Host ID: 86 Created run 88 remote on Host ID: 87 All processes have been assigned Checking if Simulation 1 is finished: not yet, next check in 120 seconds ( 0% done). q = -0 state1 = 0 state2 = 0 bond_type = 0 zero matrix element in remove_jump application called MPI_Abort(MPI_COMM_WORLD, -2) - process 67 Could somebody advice what I can do? Best regards Kuba

2 2

Quantum Wang-Landau algorithm question: applicability of QWL on frustrated lattices
by Prsa Krunoslav 02 Nov '09

02 Nov '09

Dear Prof. Troyer, Thanks for your answer. Yes, the lattice is 3D; and no, the frustration is not strong. I will follow your advice then: I'll try the QWL for the non-frustrated case, and with looper add points on the frustrated side of the phase diagram, if that will be feasible. All the best, Kruno > No, the current QWL code cannot do that. It is best to use the looper > code. Are you talking about 3D lattices? If frustration is strong the > sign problem will make simulations impossible at T_N. > Matthias > On 29 Oct 2009, at 12:20, Prsa Krunoslav wrote: > Dear ALPS maintainers, > Since nobody has yet answered to my questions from almost a month > ago, I will repeat just one question this time. > > Can the current incarnation of the QWL code handle frustrated > lattices? Specifically, I want to find the transition temperature as > a function T_N(J2/J1), where J2 and J1 are antiferromagnetic. > > > All the best, > Kruno > > --------------------------------------- > Krunoslav Prsa, Ph. D. Student > Laboratory for Neutron Scattering > Paul Scherrer Institute and ETH-Zürich > CH-5232 Villigen PSI, Switzerland > tel: +41 56 310 20 91 > mob: +41 76 386 17 99 > ---------------------------------------- > > > > -----Original Message----- > From: Prsa Krunoslav > Sent: Friday, October 02, 2009 2:56 PM > To: comp-phys-alps-users at phys.ethz.ch > Subject: Quantum Wang-Landau algorithm question: applicability of > QWL on (slightly) frustrated lattices > > > Dear ALPS maintainers, > > I have three questions with regards to your extremely powerful QWL > algorithm. > > 1. In the ALPS online documentation section for QWL algorithm there > is a note: > "Note: This first version allows the simulation of isotropic > Heisenberg spin-1/2 ferro- and antiferromagnetic models on arbitrary > non-frustrated lattices at zero magnetic field. In the future, we > plan to relax this constraint, and also provide an implementation of > the QWL perturbation expansion. " > > Has this been improved with regards to antiferro- frustrated > lattices? I am using ALPS version 1.3.3. > > 2. When I run the qwl for my slightly frustrated S=1/2 3D lattice > (consisting of triangular antiferro patterns J1-J1-J2 with J2~0.15 > J1) the program does not seem to complain (It does not seem to > complain even for the triangular lattice). Can its output for this > situation be trusted though? > > 3. I was also wondering if I can generally verify the results (say > T_N) of the frustrated model by an extrapolation from the non- > frustrated side (say ferro J2=-0.5,...,-0.1,0), thereby assuming a > mean-field like behaviour T_N~(J1-J2), for small J2. I am an > experimentalist so I may not be aware of this. Is there a general > result that would say it's not possible or at least a counterexample? > > It may be of relevance to some of the questions that in this lattice > there is a change in the classical ground state from Neel to the > triangular at J2=J1/3. > > All the best, > Kruno > > --------------------------------------- > Krunoslav Prsa, Ph. D. Student > Laboratory for Neutron Scattering > Paul Scherrer Institute and ETH-Zürich > CH-5232 Villigen PSI, Switzerland > tel: +41 56 310 20 91 > mob: +41 76 386 17 99 > ---------------------------------------- --------------------------------------- Krunoslav Prsa, Ph. D. Student Laboratory for Neutron Scattering Paul Scherrer Institute and ETH-Zürich CH-5232 Villigen PSI, Switzerland tel: +41 56 310 20 91 mob: +41 76 386 17 99 ----------------------------------------

2 1

Quantum Wang-Landau algorithm question: applicability of QWL on frustrated lattices
by Prsa Krunoslav 29 Oct '09

29 Oct '09

Dear ALPS maintainers, Since nobody has yet answered to my questions from almost a month ago, I will repeat just one question this time. Can the current incarnation of the QWL code handle frustrated lattices? Specifically, I want to find the transition temperature as a function T_N(J2/J1), where J2 and J1 are antiferromagnetic. All the best, Kruno --------------------------------------- Krunoslav Prsa, Ph. D. Student Laboratory for Neutron Scattering Paul Scherrer Institute and ETH-Zürich CH-5232 Villigen PSI, Switzerland tel: +41 56 310 20 91 mob: +41 76 386 17 99 ---------------------------------------- -----Original Message----- From: Prsa Krunoslav Sent: Friday, October 02, 2009 2:56 PM To: comp-phys-alps-users(a)phys.ethz.ch Subject: Quantum Wang-Landau algorithm question: applicability of QWL on (slightly) frustrated lattices Dear ALPS maintainers, I have three questions with regards to your extremely powerful QWL algorithm. 1. In the ALPS online documentation section for QWL algorithm there is a note: "Note: This first version allows the simulation of isotropic Heisenberg spin-1/2 ferro- and antiferromagnetic models on arbitrary non-frustrated lattices at zero magnetic field. In the future, we plan to relax this constraint, and also provide an implementation of the QWL perturbation expansion. " Has this been improved with regards to antiferro- frustrated lattices? I am using ALPS version 1.3.3. 2. When I run the qwl for my slightly frustrated S=1/2 3D lattice (consisting of triangular antiferro patterns J1-J1-J2 with J2~0.15 J1) the program does not seem to complain (It does not seem to complain even for the triangular lattice). Can its output for this situation be trusted though? 3. I was also wondering if I can generally verify the results (say T_N) of the frustrated model by an extrapolation from the non-frustrated side (say ferro J2=-0.5,...,-0.1,0), thereby assuming a mean-field like behaviour T_N~(J1-J2), for small J2. I am an experimentalist so I may not be aware of this. Is there a general result that would say it's not possible or at least a counterexample? It may be of relevance to some of the questions that in this lattice there is a change in the classical ground state from Neel to the triangular at J2=J1/3. All the best, Kruno --------------------------------------- Krunoslav Prsa, Ph. D. Student Laboratory for Neutron Scattering Paul Scherrer Institute and ETH-Zürich CH-5232 Villigen PSI, Switzerland tel: +41 56 310 20 91 mob: +41 76 386 17 99 ----------------------------------------

2 1

plotting...
by Muhammad Rofiq 29 Oct '09

29 Oct '09

Dear Mr. Troyer I've some problem to plot of LATTICE GRAPH, how to get a figure of my latticegraph? can it use xmgr? Thanks before, Akses email lebih cepat. Yahoo! menyarankan Anda meng-upgrade browser ke Internet Explorer 8 baru yang dioptimalkan untuk Yahoo! Dapatkan di sini! http://downloads.yahoo.com/id/internetexplorer

3 2

Extract data in 2D Heisenberg Model
by Simon Ketterer 24 Oct '09

24 Oct '09

Dear Matthias Troyer, For getting used with alps I've tried to extract the Spin Correlations location (index) and the Spin Correlations (mean value) itself of the 2D Heiseberg Model. Could you please suggest me how to insert the commands in the plot.xml file for extracting these data? I'd be very grateful if you could give some advice! Best regards Simon Ketterer TCD

2 1

spin interaction
by Muhammad Rofiq 04 Oct '09

04 Oct '09

Dear Mr. Troyer.. I've some problem about my Thesis, I would like to get solution about these.. my problems are: 1. Can the ALPS use to simulate spin interction and energy of CdMnTe? 2. if it can, what is the method to simulate spin interction and energy of CdMnTe? DMRG or the other method?and 3. what is the syntax program about it? Thanks before..... Lebih aman saat online. Upgrade ke Internet Explorer 8 baru dan lebih cepat yang dioptimalkan untuk Yahoo! agar Anda merasa lebih aman. Gratis. Dapatkan IE8 di sini! http://downloads.yahoo.com/id/internetexplorer/

1 0

Quantum Wang-Landau algorithm question: applicability of QWL on (slightly) frustrated lattices
by Prsa Krunoslav 02 Oct '09

02 Oct '09

Dear ALPS maintainers, I have three questions with regards to your extremely powerful QWL algorithm. 1. In the ALPS online documentation section for QWL algorithm there is a note: "Note: This first version allows the simulation of isotropic Heisenberg spin-1/2 ferro- and antiferromagnetic models on arbitrary non-frustrated lattices at zero magnetic field. In the future, we plan to relax this constraint, and also provide an implementation of the QWL perturbation expansion. " Has this been improved with regards to antiferro- frustrated lattices? I am using ALPS version 1.3.3. 2. When I run the qwl for my slightly frustrated S=1/2 3D lattice (consisting of triangular antiferro patterns J1-J1-J2 with J2~0.15 J1) the program does not seem to complain (It does not seem to complain even for the triangular lattice). Can its output for this situation be trusted though? 3. I was also wondering if I can generally verify the results (say T_N) of the frustrated model by an extrapolation from the non-frustrated side (say ferro J2=-0.5,...,-0.1,0), thereby assuming a mean-field like behaviour T_N~(J1-J2), for small J2. I am an experimentalist so I may not be aware of this. Is there a general result that would say it's not possible or at least a counterexample? It may be of relevance to some of the questions that in this lattice there is a change in the classical ground state from Neel to the triangular at J2=J1/3. All the best, Kruno --------------------------------------- Krunoslav Prsa, Ph. D. Student Laboratory for Neutron Scattering Paul Scherrer Institute and ETH-Zürich CH-5232 Villigen PSI, Switzerland tel: +41 56 310 20 91 mob: +41 76 386 17 99 ----------------------------------------

1 0