March 2009 - Comp-phys-alps-users

current correlation function for fermionic hubbard model
by khalid hassan 30 May '09

30 May '09

Can alps can calculate the current correlation function for the fermionic hubbard model model for say two site. I have been using alps to calculate cahrge coorelation function the charge correlation function is < n_i n_j > = < c_i^+ c_i c_i^+ c_i > where as the current correlation function is < j_i j_j > = < c_i^+ c_j c_k^+ c_l > see the changing indexes. If it is possible then send me the program statement Best regards Khalid Loane

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Kondo lattice in ALPS
by Fu-Jiun Jiang ITP 20 May '09

20 May '09

Hello all, I got 2 questions for the Kondo lattice in the ALPS. The Hamiltonian in the models.xml for Kondo lattice reads -t*fermion_hop(i,j) + J*exchange(i,j) 1. Does the code only work at half-filling? 2. The second term in the Hamiltonian does not look like the original one, namely, the original Hamiltonian of the Kondo model contains a term \sum_{i} s_i \cdot S_i, here the s (S) are the spin of the conducting (local) electrons. I wonder what's going on. Thank you very much for your attention. Sincerely, Fu-Jiun

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alps in ubuntu hardy
by sinan bulut 17 Apr '09

17 Apr '09

Does anyone know or have experience on how to install alps in ubuntu(hardy 8.04) ? I tried to install it from the source using "configure, make ... etc" commands but it did not work.

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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, > > > 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> > > > > > > There is a solution which looks ugly, but works : > > patch the definition of the site basis of the model you're working > with. > In your example, Bose-Hubbard Hamiltonian uses the basis called > "boson". > Go to models.xml file and then add a line to the SITEBASIS definition: > > <SITEBASIS name="boson"> > <PARAMETER name="Nmax" default="infinity"/> > <QUANTUMNUMBER name="N" min="0" max="Nmax"/> > <OPERATOR name="bdag" matrixelement="sqrt(N+1)"> > <CHANGE quantumnumber="N" change="1"/> > </OPERATOR> > <OPERATOR name="b" matrixelement="sqrt(N)"> > <CHANGE quantumnumber="N" change="-1"/> > </OPERATOR> > <OPERATOR name="n" matrixelement="N"/> > <OPERATOR name="n2" matrixelement="N*N"/>  > </SITEBASIS> > > Like I said, it's ugly, but it works. > And, like you, I'd be very much interested in learning how to add > measurements properly, without dirty tricks :). > > > Best, > > > Zhenya > > > End of Comp-phys-alps-users Digest, Vol 36, Issue 16 > ****************************************************

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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 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 > ****************************************************

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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 references (28/102) are from groups of authors that do not include an ALPS developer. For a complete list go to https://alps.ethz.ch/mediawiki/index.php/PapersTalks #Papers_citing_the_ALPS_project Best regards, Simon

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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: cm3*mol-1, the unit of chi_sse: cm. Na: Avogadro constant, 6.022*10^23 mol-1 mu_b: Bohr magneton, 9.274*10^(-21) emu(A)*cm^2 g: Lange factor Is it right? If not,what is it? I really hope you to help me! Thank you a lot!

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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=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 > > **************************************************** > > >

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dynamical correlation functions
by jessica.alfonsi＠unipd.it 23 Mar '09

23 Mar '09

Hello everybody, I'm interested in starting using ALPS project, in particular for computing optical spectral functions starting from exact diagonalization and dynamical correlation function for optical conductivity. However, I read in papers about ALPS 1.3 release that these will be implemented in release 1.4 . When do you plan to release at least the first beta of ALPS 1.4 ? Is it possible to use a patched SVN version ? Thank you and best wishes Jessica Alfonsi

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