Comp-phys-alps-users

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1248 discussions

current correlation function for fermionic hubbard model using alps
by khalid hassan 27 Feb '09

27 Feb '09

I am using alps for the calculation of charge correlation function for the fermionic hubbard model. Now I want to calculate the current correlation function. the expression for the charge correlation function is < n_i : n_j > = < c_i^+ c_i : c_j^+ c_j > the expression for the current correlation function is < j_i : j_j > = < c_i^+ c_j : c_k^+ c_l > Notice the changing indices in the current expression. If it is possible then please give the program statements doing this Best Regards Khalid Loane

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Simple graphs and complex hopping parameter(t)
by Akinlolu Akande 09 Feb '09

09 Feb '09

Hi all, Is it not possible to define a simple graph with complex hopping parameter in the Hamiltonian when using fulldiagonization? For example, a 4-site chain is defined using a simple graph as <LATTICES> <GRAPH name="Chain" vertices=" 4"> <VERTEX id=" 1" type="0"></VERTEX> <VERTEX id=" 2" type="0"></VERTEX> <VERTEX id=" 3" type="0"></VERTEX> <VERTEX id=" 4" type="0"></VERTEX> <EDGE type="0" source=" 1" target=" 2"/> <EDGE type="0" source=" 2" target=" 3"/> <EDGE type="0" source=" 3" target=" 4"/> </GRAPH> </LATTICES> which I could also use the lattices.xml in the lattice libraries.I discovered that when the lattice in the libraries is used, it works well for complex hopping but using a simple graphs I got the following errors 'can not convert complex number into real one'.Any reason for this error?The reason I want to use a simple graph is because I want to use a different lattice structure for my calculations. Thanks Akin

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definition of energy density/heat capacity
by Fritz Koermann 08 Feb '09

08 Feb '09

Hi alps community, does the "Energy Density" output in the classical spinmc correspond to the (Total Energy)/spins and the analogue "Energy Density in the quantum case, e.g. using loop, to (Total Energy)/volume? Since for simple cubic systems both energy densities are equal but for a simple bcc lattice they differ by a factor of 2 so I wonder if they are differently defined? If so, does the same apply consistently to the calculated heat capacities (are they calculated using the fluctuations of the corresponding energy densities)? Best, Fritz --- Max-Planck-Institut für Eisenforschung GmbH Max-Planck-Straße 1 D-40237 Düsseldorf Handelsregister B 2533 Amtsgericht Düsseldorf Geschäftsführung Prof. Dr. Jörg Neugebauer Prof. Dr. Dierk Raabe Prof. Dr. Martin Stratmann Dipl.-Kfm. Herbert Wilk Ust.-Id.-Nr.: DE 11 93 58 514 Steuernummer: 105 5891 1000 -------------------------------------------------

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Measurements
by Jakub Zakrzewski 04 Feb '09

04 Feb '09

Hello All, coould someone more experienced than me could explain briefly what type of measurements (averages of observables) may be extracted from current version. I am most interested in boson model now but question is more general. The section on parameters/measurements is unfortunately missing in wiki... Example: MEASURE_LOCAL[Local density]=n allows to get occupation of sites <n_i> for Bose-Hubbard. (Thanks, Akin, for this example). Probably other averages can be extracted but how? I tired a second moment by typing simply MEASURE_LOCAL[Local density^2]=n2 that for sparse/full diagonalization gives (e.g. sparse) Cannot evaluate expression n2(i) similarly for MEASURE_LOCAL[Compressibility]=kappa [actually in one of the files kappa(i) seems to be evaluated as it should from n2(i) and n(i) ] Worm algorithm in QMC yields: Will not measure "Compressibility" since it is off-diagonal or not a site operator Will not measure "Local density^2" since it is off-diagonal or not a site operator (which are apparently incorrect comments anyway) anybody kind enough to help? Best wishes kuba

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kinetic and potential energy
by Akinlolu Akande 03 Feb '09

03 Feb '09

Hello all, I am just curious to know whether it is possible to write out individually the kinetic energy term and potential energy term of the ground state energy using full diagonization/sparse diagonization/etc.If yes, how is it done? Best Regards. Akin

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Extending a simulation
by Jakub Zakrzewski 29 Jan '09

29 Jan '09

Hello, I am fresh, just trying ALPS, so question may be trivial. How to "extend a simulation" in QMC (worm). Info in wiki: http://alps.comp-phys.org/mediawiki-1.9.3/index.php/Running says to increase the amount of sweeps (which I did) and set a simulation status ti running from finished. But where to set it? Example -- ... is missing... Help appreciated KubaZakrzewski

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Re: [ALPS-users] extending a simulation
by Jakub Zakrzewski 29 Jan '09

29 Jan '09

Thanks to all who answered. Synge - your practical advice most appreciated. I do not know whether it applies to all MC-codes. I run QMC (worm) on different twists of Bose-Hubbard. Mathias. Thanks. That I found after asking. BUT still- ... you wrote > Date: Wed, 28 Jan 2009 09:31:00 -0800 > From: Matthias Troyer <troyer(a)phys.ethz.ch> > > If your parameters are called parms, then parameter2xml creates a file > > parms.in.xml, and the simulation creates a file parms.out.xml . The > latter is the file to edit. > I did exactly as you suggest - My parameter file is called prl I changed status from "finished" to "running" in prl.out.xml. I increased SWEEPS in prl.task1.out.xml. Then I execute worm --Tmin 50 parms.out.xml and get info: - I copy the screen here kuba@b52:~/Pr3 $ worm --Tmin 50 prl.out.xml Worm algorithm quantum Monte Carlo simulation v2.0 copyright (c) 1997-2007 by Simon Trebst <trebst(a)comp-phys.org> and Matthias Troyer <troyer(a)comp-phys.org> for details see the publication: A.F. Albuquerque et al., J. of Magn. and Magn. Materials 310, 1187 (2007). using the ALPS parallelizing scheduler copyright (c) 1994-2006 by Matthias Troyer <troyer(a)comp-phys.org>. see Lecture Notes in Computer Science, Vol. 1505, p. 191 (1998). based on the ALPS libraries version 1.3.3 available from http://alps.comp-phys.org/ copyright (c) 1994-2008 by the ALPS collaboration. Consult the web page for license details. For details see the publication: A.F. Albuquerque et al., J. of Magn. and Magn. Materials 310, 1187 (2007). parsing task files ... Loading information about run 1 from file /users/champ/kuba/Pr3/prl.task1.out.run1 Cannot change parameter SWEEPS Cannot open simulation file /users/champ/kuba/Pr3/prl.task1.out.xml. Task 1 does not exist. Finished with everything. Please note the info Cannot change parameter SWEEPS. So what I am doing wrongly? regards Kuba (Jakub Zakrzewski)

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Problem in Running the Program
by zhian asadzadeh 27 Jan '09

27 Jan '09

Dear All I installed the ALPS package successfully but when I tried to run the program gave following error: *error while loading shared libraries: libmkl_lapack.so: cannot open shared object file: No such file or directory* I have lapack library on my system, too. Thanks Zhian

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Re: [ALPS-users] one solution to compilation issues with GCC (Jeff Hammond)
by Tadeusz Wasiutynski 27 Jan '09

27 Jan '09

Thank you Jeff, now it works fine. I did not face above problem with older compiler. Tadeusz On Sun, 25 Jan 2009 12:00:03 +0100, comp-phys-alps-users-request wrote > > What do you mean break? GCC 4.3.1 segfaulted on the compilation of > spinmc_factory.C: > > ============================================== > g++ -DHAVE_CONFIG_H -I. -I. -I../.. -DNDEBUG > -I/software/alps/include -I/software/alps/boost_1_37_0 > -I/software/alps/include -I/software/alps/lp_solve_4.0 -pthread > -ftemplate-depth-150 -O3 -DBOOST_DISABLE_ASSERTS -fexceptions -w -MT > spinmc_factory.o -MD -MP -MF .deps/spinmc_factory.Tpo -c -o > spinmc_factory.o spinmc_factory.C > spinmc_factory.C: In constructor > 'AbstractSpinSim<MAT>::AbstractSpinSim(const alps::ProcessList&, > const alps::Parameters&, int) [with MAT = DiagMatrix<double, 3>]': > spinmc_factory.C:194: internal compiler error: Segmentation fault > Please submit a full bug report, with preprocessed source if appropriate. > See <http://bugs.opensuse.org/> for instructions. > make: *** [spinmc_factory.o] Error 1 > ============================================== > > but it compiled when I changed the "-O3" in CXXFLAGS "-O0" (both "- > O2" and "-O1" failed as well for the same reasons) I was able to compile > that file. I then stopped the build after the spinmc_factory.o was > formed, restored optimization to the default, and the rest of ALPS > compilation went fine. > > I should have mentioned this the last time but I wasn't sure if it > was just by distro that had this issue. I have 4 GB so the segfault > is certainly a bug not the absence of sufficient memory. > > I have not reported this bug to GCC because such things usually > require posting the code that fails and I have no hope of doing this > properly without including all of ALPS/Boost. It would be great it > someone at ALPS who is closer to the GCC project could do so though. > > Jeff > > On Sat, Jan 24, 2009 at 4:52 AM, Tadeusz Wasiutynski > <Tadeusz.Wasiutynski(a)ifj.edu.pl> wrote: > > > > > > Indeed the compilation of ALPS-1.3.3 goes smoothly with gcc-4.3.1 and > > boost-1.37. Unfortunately alps-applications compilation breaks on > > spinmc.factory while was not the case with older gcc. All other prerequisities > > but lp_solve come in the system. Any suggestions? > > Shall we compare all the components incl kernel? > > Tadeusz > > > > > > -- > Jeff Hammond > The University of Chicago > http://home.uchicago.edu/~jhammond/ > > End of Comp-phys-alps-users Digest, Vol 34, Issue 9 > ***************************************************

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2D Heisenberg model with open boundary in one spatial direction
by Fu-Jiun Jiang ITP 26 Jan '09

26 Jan '09

Hello all I think I should try to make my quick questions more precise (hence slightly more interesting). For a 2D Heisenberg model with open boundary in one spatial direction, can one measure the spin-spin correlations as well as the on-site magnitization as functions of distance from the open boundary using ALPS without modifying the codes dramatically? Thanks in advance! Sincerely, FJ

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Comp-phys-alps-users