Comp-phys-alps-users

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1248 discussions

specific heat measurements
by Brian Keith 11 Sep '08

11 Sep '08

Hello, I looked at the alps tutorial pages and it says that the looper code calculates specific heat. I ran the looper code from alps version 1.3.3. I looked at the task.out files and specific heat was not listed anywhere. Am I missing something? -thanks, Brian

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Finding the site at a particular set of coordinates
by Miles Stoudenmire 11 Sep '08

11 Sep '08

Hi - I'm trying to write a custom measurement in the classical spin mc code, and I'd like to be able to have the alps lattice library tell me the site that is at a given location relative to another site. More specifically, I'd like to start with pair of sites, indices i and j, then compute the vector v=(r_j-r_i) (this I already know how to do using the coordinates function). Then, I'd like to go to some other site, k, and figure out the index, l, of the site at r_k + v (i.e. I want (r_l-r_k) = (r_j-r_i)). Is there a general way to do this using the alps lattice library or will I have to write special code for the particular lattice that I'm using? Thanks! -- -=Miles Stoudenmire=- miles(a)physics.ucsb.edu miles.stoudenmire(a)gmail.com http://www.crazytheory.com/

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Wang-Landau method for qm spin system
by Fritz Koermann 07 Sep '08

07 Sep '08

Hi Matthias, dear alps community, is it possible to use the qmc wang-landau method for the qm Heisenberg model as implemented in alps also in combination with more than nearest-neighbour exchange J (still unfrustrated lattice)? Thanks for the wonderful support, 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. Anke R. Pyzalla 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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Wang-Landau method for classical spin system
by Fritz Koermann 04 Sep '08

04 Sep '08

Dear alps users, is the Wang-Landau method also available within alps for the classical monte carlo package or is it planned to be implemented? 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. Anke R. Pyzalla 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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Re: [ALPS-users] Comp-phys-alps-users Digest, Vol 29, Issue 8
by João Manuel Viana Parente Lopes 03 Sep '08

03 Sep '08

Dear Matthias Troyer and Synge Todo, I'm sorry for the late response but I was away from my computer several days! Thank's for your help!! I increased the number of SWEEPS and I have finally found the square root behaviour of the error bars as a function of the number of SWEEPS. I imagine (I didn't had time to check yet) the method of estimation of the error bars makes an underestimation of the variance. Thanks again for your time João Lopes

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Re: [ALPS-users] First alps trials : Decreasing error bars
by João Manuel Viana Parente Lopes 29 Aug '08

29 Aug '08

On Aug 28, 2008, at 11:00 AM, comp-phys-alps-users- request(a)phys.ethz.ch wrote: > Send Comp-phys-alps-users mailing list submissions to > comp-phys-alps-users(a)phys.ethz.ch > > To subscribe or unsubscribe via the World Wide Web, visit > https://webmail.phys.ethz.ch/mailman/listinfo/comp-phys-alps-users > or, via email, send a message with subject or body 'help' to > comp-phys-alps-users-request(a)phys.ethz.ch > > You can reach the person managing the list at > comp-phys-alps-users-owner(a)phys.ethz.ch > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of Comp-phys-alps-users digest..." > > > Today's Topics: > > 1. First alps trials (Jo?o Manuel Viana Parente Lopes) > 2. Re: First alps trials (Matthias Troyer) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Wed, 27 Aug 2008 23:56:53 +0100 > From: Jo?o Manuel Viana Parente Lopes <jvianalopes(a)gmail.com> > Subject: [ALPS-users] First alps trials > To: comp-phys-alps-users(a)phys.ethz.ch > Message-ID: <40B2C500-9E6E-45A9-A170-91187657132C(a)gmail.com> > Content-Type: text/plain; charset="iso-8859-1" > > Dear colleagues, > > I'm making my first experiments with Alps... > I was comparing the average energy for small temperatures (T~ 0.01, J > = 1) in the 1D Heisenberg model > with the exact solution for small open linear chains using the loop > program with de SSE representation. > > I notice that I can not decrease the error bars by the increase of > the numbers of SWEEPS! > How can I decrease the error bars? > > Thanks in advance > > Jo?o Lopes > > PS: A sugestion: It would be very helpful if we could do a search in > the mailing list > Maybe this link could help: http://wiki.list.org/display/DOC/How+do+I > +make+the+archives+searchable > >

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First alps trials
by João Manuel Viana Parente Lopes 28 Aug '08

28 Aug '08

Dear colleagues, I'm making my first experiments with Alps... I was comparing the average energy for small temperatures (T~ 0.01, J = 1) in the 1D Heisenberg model with the exact solution for small open linear chains using the loop program with de SSE representation. I notice that I can not decrease the error bars by the increase of the numbers of SWEEPS! How can I decrease the error bars? Thanks in advance João Lopes PS: A sugestion: It would be very helpful if we could do a search in the mailing list Maybe this link could help: http://wiki.list.org/display/DOC/How+do+I +make+the+archives+searchable

2 1

Correlation function and complex lattices
by sadegh raeisi 25 Aug '08

25 Aug '08

Dear all, I have defined a graphlattice which has 2 particles on each site. In other words the unit cell includes 2 vertices. But I encountered a problem using this lattice. the problems is about the correlation functions. For instance, when I want to calculate the <SzSz> correlation function( MEASURE_CORRELATIONS[Diagonal spin correlations]=Sz ) it seems that ALPS calculates the corresponding function between sites of the lattice instead of particles(vertices) on a sites. Also there is noway to calculate the correlation functons between particles on one site. I will be grateful if any one can help me. Best regards S. Raeisi ---------------------------------------------- Sadegh Raeisi Department of Physics Sharif University of Technology Quantum Information Group ----------------------------------------------

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Ising/Potts-like Heisenberg simulation
by Fritz Koermann 23 Aug '08

23 Aug '08

Hi, is it possible to define a kind of 'Ising-type' or Potts-like model for the 3D Heisenberg MC simulation as in PRB 72,134426, where the unit vectors are restricted to lie on a cone defined by a discrete spin-z-component Sz=-S,...+S? For S=1/2 this would correspond to the usual Ising model. Is it possible to define therefor a spin number, lets say S, so that the z-component is restricted to have a value between -S and +S where the x- and y-components are still chosen randomly? Best and thanks for the great support! 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. Anke R. Pyzalla 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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CECAM
by Matthias Troyer 17 Aug '08

17 Aug '08

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