Comp-phys-alps-users

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1244 discussions

basis states along with corresponding energies
by khalid hassan 09 Apr '09

09 Apr '09

Dear alps team, I asked for the basis staties and hamiltonian matrix for the system described by parameters in case of exact diagonalization. Dr Matthias Troyer told me of a program in alps/model directory. This program is print_numeric and it displays the basis states and hamiltonian matrix. Now I am interested with the basis states of lowest energy, as in case case of sparsediag which only has lowest energy states or fulldiag with firse states. I want that as sparse diag or full diag give … [View More]

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DMRG question
by Justin David Peel 07 Apr '09

07 Apr '09

Hi all, I hope this is okay to ask here, but I didn't know where else to ask it. I've been trying to do a different periodic DMRG algorithm that splits the first site so that it is in both the left and right blocks. This is in trying to do a DMRG algorithm kind of like the matrix product state sort that works so much better. I've been having some problems with doing this and was wondering if anyone had any ideas. I'm only considering a 1D Heisenberg S=1/2 model for now. First of all, I keep … [View More]

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configure flags for ALPS applications
by Andrea Taroni 07 Apr '09

07 Apr '09

Dear All, I am having trouble installing ALPS applications on a Ubuntu 8.04 system. Installing the libraries is not a problem. Installing the applications wouldn't be, if I were not interested in including the lapack libraries in the installation. I've followed the instructions for the setup and installation of the applications, where it states that adding the option --with-lapack=-lLIB when running configure "specifies the library files for the LAPACK libraries". When I do this, I get an … [View More]

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Classical Heisenberg model
by Gianni Profeta 06 Apr '09

06 Apr '09

Dear users, I'm trying to perform classical MC simulation for the 3D Heisenberg model. The model is formed by random magnetic impurities in periodic lattice interacting with different Jij for various neighboring distances r between the magnetic sistes (i and j). Any suggestions on how to define different J's between different sites? Thanks a lot, Gianni

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Re: [ALPS-users] working on alps code
by Jakub Zakrzewski 28 Mar '09

28 Mar '09

Dear Zhenya, Many thanks!! It is not ugly it is beautiful and it works !! All the best jakub > Message: 3 > Date: Fri, 27 Mar 2009 21:48:00 +0100 > From: Evgeny Burovskiy <burovski(a)alumni.umass.edu> > Subject: Re: [ALPS-users] working on alps code > To: comp-phys-alps-users(a)phys.ethz.ch > Message-ID: <49CD3B80.9080803(a)physik.uni-greifswald.de> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > > Dear Jakub, > > > … [View More]

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Re: [ALPS-users] working on alps code
by Jakub Zakrzewski 27 Mar '09

27 Mar '09

Dear Matthias, 1. I congratulate you and your colleagues for creating such a fantastic tool as ALPS is. 2. See point 1. 3. Still there is a lot of truth in what Khalid Hassan wrote. To be specific: - I cannot go to Zurich for personal consultation. Both from Paris where I am on sabbatical and from Krakow (POland) it is a bit too far just for asking a couple of simple questions. Instead I go to Tutorial and Documentation link on https://alps.ethz.ch/mediawiki/index.php/Main_Page and want … [View More]to read about: Definition of custom measurements or Common hardcoded measurements to know what I can get. But these sections of the Documentation are EMPTY. So I guess from examples .. but I cannot guess everything. To be specific. I run QMC codes for Bose-Hubbard. I know how to get occupation at different sides (for inhomogenous model, e.g. with harmonic trap and/or disorder), call them <n_i>. But I am interested in second moment <n_i^2> What I can do? a/ I wrote a long email to you b/ 2 times I posed questions on the very same subject on this list without getting any answer. From more experienced colleague, I learn that I may modify qmc.h so I get <n_i^2> INSTEAD of <n_i> - but this requires recompilation of applications and running the whole simulation twice. There MUST be a more intelligent way of getting the info I need. Or correlations <a_i a_j^\dagger> or <n_i n_j> .... May somebody give an advice on that? 4. Simon Trebst was happy that you reached 100 citations to ALPS (I guess this is both to old and new reference). I bet you, were there more user friendly documentation available and more active list of users, the number of citations would increase tremendously... I am sure that at least by 1 since the things we work on now (with ALPS) could be finished in a more reasonable ammount of time... All the best Jakub > > > > ------------------------------ > > Message: 2 > Date: Thu, 26 Mar 2009 20:19:22 -0700 > From: Matthias Troyer <troyer(a)phys.ethz.ch> > > Dear Khalid Loane, > > The ALPS libraries are meant to be used in user code, and are > documented. The applications had been designed as black box codes. > However, if you would like to learn more about them and work on one of > > them, we will be delighted to help. Best would be a personal visit > though to explain the code structure - and clean it up while doing that. > > Matthias > > > > > On 26 Mar 2009, at 14:12, khalid hassan wrote: > > > > > alps is a program that works well with a comprehensive help. but if > > > one has use its code for one self research, the code provides little > > > help. it has very few comments and difficult to understand. Can > > there can be any help for the code of full diagonalization for > > example logical structure, flow chart, algorithm available. If this > > > is in personal files of the developers can they send by email or if > > > someone visits them they can give him. > > > > Best Regards > > Khalid Loane > > ITCP, Graz Austria > > > > > > > > > > End of Comp-phys-alps-users Digest, Vol 36, Issue 15 > **************************************************** [View Less]

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working on alps code
by khalid hassan 27 Mar '09

27 Mar '09

alps is a program that works well with a comprehensive help. but if one has use its code for one self research, the code provides little help. it has very few comments and difficult to understand. Can there can be any help for the code of full diagonalization for example logical structure, flow chart, algorithm available. If this is in personal files of the developers can they send by email or if someone visits them they can give him. Best Regards Khalid Loane ITCP, Graz Austria

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An ALPS milestone
by Simon Trebst 26 Mar '09

26 Mar '09

Dear fellow ALPS developers and users, in recent days the ALPS project has passed yet another milestone -- we have now collected more than 100 publications citing the ALPS project. Congratulations everyone! I think it's also quite interesting to take a closer look at these references: Out of the 102 references, 84 are published articles, 18 are preprints. More than a quarter of all published articles (23/84) are PRLs -- an unusually high percentage. And more than a quarter of all … [View More]

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uniform magnetic susceptibility
by Guilin Zhuang 24 Mar '09

24 Mar '09

Dear All prof. As for chemistry major, the QMC and magnetic knowledge is not enough for me ! Here I ask the same question again! In the simulation of SSE by the version 1.2.2 of ALPS, I have to know the conversion factor between the molar magnetic susceptibility and uniform magnetic susceptibility. I produce the following equation between them. If the dimension for couple parameter J is cm-1, and conversion equation: chi_mol=Na * mu_b * g * chi_sse The unit of chi_mol: … [View More]

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Energy Gap
by zhian asadzadeh 24 Mar '09

24 Mar '09

Hi Dear, I tried to calculate energy gap for ferrimagnetic ladder. in this paper ( Phy Rev B, 63, 054432) it has been done which you can find in table I. I used the periodic boundary condition because in the case of open boundary condition the energy converges very slowly. I have achieved the following result. E0= -0.757036 E1= -0.757032 I have used the following input file: I have tried for inter chain coupling J' = 0.2 with the notation of this paper. LATTICE="ferrimagnetic ladder" SWEEPS=… [View More]4 MAXSTATES=300 MODEL="spin", L=30 local_S0=1/2,local_S1=1,Jxy0=1,h=0.0,Jxy1=0.2,Jz1=0.2 BC1=periodic,BC2=periodic NUMBER_EIGENVALUES=2 Jz0=1 {Gamma=0.0;} which L is the number of unit cell and h, Gamma are longitudinal and transverse magnetic field respectively. Jz0 , Jxy0 are chain couplings and Jz1, and Jxy1 are inter chain couplings. we see that the result is not concur with this paper for energy gap. I see in this paper lanczos method is used but I expect that the result be same in 4 digit. please let me know what is wrong? Thanks, Mohammad. On Wed, Mar 18, 2009 at 2:30 PM, <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. Energy Gap (zhian asadzadeh) > 2. Re: Energy Gap (Matthias Troyer) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Tue, 17 Mar 2009 14:43:46 +0330 > From: zhian asadzadeh <zhian.asadzadeh(a)gmail.com> > Subject: [ALPS-users] Energy Gap > To: comp-phys-alps-users(a)phys.ethz.ch > Message-ID: > <89e5d6760903170413w7e72ef85i873b8d47564f4320(a)mail.gmail.com> > Content-Type: text/plain; charset="iso-8859-1" > > Hi Dear, > > Thank you for your consideration. > My model is anisotropic Ferrimagnetic chain in transverse magnetic field. > when I say the result is wrong I mean when I have tried to obtain energy > gap > for some problems and models which have been solved earlier I saw the > result doesn't agree with those earlier results. for example spin one and > half-one chain and ferrimagnetic chain and anisotropic ferrimagnetic > ladder. > Something is not very obvius for me, how DMRG calculate ground state and > first exited state from one wave function ?! > > Thanks, > Zhian. > > > On Tue, Mar 17, 2009 at 2:30 PM, > <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. Re: Energy Gap (Matthias Troyer) > > > > > > ---------------------------------------------------------------------- > > > > Message: 1 > > Date: Mon, 16 Mar 2009 12:33:11 -0700 > > From: Matthias Troyer <troyer(a)phys.ethz.ch> > > Subject: Re: [ALPS-users] Energy Gap > > To: comp-phys-alps-users(a)phys.ethz.ch > > Message-ID: <43E825E5-7BE3-4EA0-9C2A-20A1FC8C21AF(a)phys.ethz.ch> > > Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes > > > > > > On Mar 16, 2009, at 2:01 AM, zhian asadzadeh wrote: > > > > > Hi All, > > > > > > I want to calculate energy gap for spin chain with DMRG. I set > > > NUM_EIGENVALUES=2 in my parm file but the result which achieved is > > > wrong. > > > Is it necessary to determine something else for example the sector > > > which DMRG work in it? in my problem I dont have any good symmetry > > > and I can not easily determine the sector which the first exited > > > state is in it. I would be very appreciate if someone could please > > > help me. > > > > > > Thanks, > > > Zhian. > > > > Can you please send more details about your model, or better yet the > > input file? An what do you mean exactly by saying that the result is > > wrong? > > > > Matthias > > > > > > > > End of Comp-phys-alps-users Digest, Vol 36, Issue 10 > > **************************************************** > > > [View Less]

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