Comp-phys-alps-users

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1248 discussions

Imaginary Operators and advanced correlation functions
by zhian asadzadeh 27 Oct '12

27 Oct '12

Dear ALPS users, I have two questions regarding DMRG application of ALPS; 1. is it possible to define imaginary operators in this new version? in the simplest case I tried for operator like Sy=1/(2*I)(S+-S-) and it seems doesn't recognise I, how should i define the imaginary part? 2. I am interested to calculate correlations like <O1O2O3> in which O's are local operators and they could be also imaginary like Sy in (<Sx(i)Sy(j)Sz(k)>? I know at the moment just correlations like <O1O2> are calculable, but I would like to know is it easy to implement the above mentioned problem or is there a kind of trick to do it? -- Sincerely yours, Zhian.

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spinmc questions
by Jonas Anderson 22 Oct '12

22 Oct '12

I have some very basic questions for which I cannot find documented answers. (1) For the Ising models or more generally for classical spin models is it possible to view the final spin configuration of a system after the simulation has run its course? (2) Is it possible to observe the magnetization and not just the absolute value of the magnetization? Thanks in advance, -jonas -- Jonas T. Anderson Post-doc Université de Sherbrooke

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tmp directory for DMRG
by benoît grémaud 19 Oct '12

19 Oct '12

Dear All, I would like to know if one can change, at runtime, the directory for temporary files used by the DMRG code. /tmp is the current location, but my / partition is rather small and get filled rapidly for large system sizes. thank you for your help. (i am using alps-2.1.1-r6176) regards, Benoît Grémaud -- -------------------- Researcher at CNRS, Laboratoire Kastler Brossel (Paris, France) Visiting Associate Professor at the Centre for Quantum Technologies (NUS, Singapore)

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question about ALPS
by hamid mosadegh 11 Oct '12

11 Oct '12

Dear ALPS user is it possible to define a distance dependent terms to Hamiltonians ,like this term, V/|i-j| I try to define this term but the program can not evaluate i & j. thanks in advance -- -- H. Mosadeq Ph.D. student of Physics, Isfahan Univ. of Technology, Isfahan 84156, Isfahan, IRAN

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ALPS 2.0.1 released
by Matthias Troyer 19 Sep '12

19 Sep '12

Dear ALPS users, ALPS 2.0.1 has been released. This is the version included with the ALPS paper: B. Bauer et al., J. Stat. Mech. (2011) P05001, which is available at : http://www.iop.org/EJ/abstract/1742-5468/2011/05/P05001 .Besides references to this paper, this release contains many minor bug fixes. The MacOS X 10.5 binary release will be uploaded shortly. The others are ready for download. Best regards Matthias Troyer

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questions about worm code
by Lev 18 Sep '12

18 Sep '12

Dear Dr. Troyer and users of ALPS, I am trying to measure local magnetization with MEASURE_LOCAL[Local magnetization]=Sx for the following model: <HAMILTONIAN name="my spin model 1"> <BASIS ref="spin"/> <SITETERM site="i"> -2*xi*Sz(i)-2*h*Sx(i) </SITETERM> <BONDTERM source="i" target="j"> -g*(Splus(i)*Sminus(j)+Sminus(i)*Splus(j)) </BONDTERM> </HAMILTONIAN> Value of parameter xi depends on the site in an actual problem, but this is not important now. Since dirloop_sse says that "Offdiagonal site terms are not implemented in this SSE code", I use the worm code. Worm code says the following for this: "Will not measure "Local magnetization" since it is off-diagonal or not a site operator". As a trick to overcome this problem, I tried to rotate the coordinate system in order to measure the required values with MEASURE_LOCAL[Local magnetization]=Sz In this case the rotated model is: <SITEOPERATOR name="Sy" site="x"> 1/2/I*(Splus(x)-Sminus(x)) </SITEOPERATOR> <HAMILTONIAN name="my spin model 2"> <BASIS ref="spin"/> <SITETERM site="i"> -2*xi*Sy(i)-2*h*Sz(i) </SITETERM> <BONDTERM source="i" target="j"> -2*g*Sz(i)*Sz(j)-2*g*Sx(i)*Sx(j) </BONDTERM> </HAMILTONIAN> Now the worm code says the following: "can not convert complex number into real one". Therefore, the worm code does not seem to understand Sy(i) as a site term in Hamiltonian (?). Finally, I tried another version of rotation, which also would allow to measure with MEASURE_LOCAL[Local magnetization]=Sz The rotated model is: <SITEOPERATOR name="Sy" site="x"> 1/2/I*(Splus(x)-Sminus(x)) </SITEOPERATOR> <HAMILTONIAN name="my spin model 3"> <BASIS ref="spin"/> <SITETERM site="i"> 2*xi*Sx(i)-2*h*Sz(i) </SITETERM> <BONDTERM source="i" target="j"> -2*g*Sz(i)*Sz(j)-2*g*Sy(i)*Sy(j) </BONDTERM> </HAMILTONIAN> Now the worm code says the following: "Cannot simulate this bond term with the worm code". Therefore, the worm code does not seem to understand Sy(i)*Sy(j) as a bond term in Hamiltonian (?). Could you let me know whether there are ways to perform the measurement ? Sincerely yours, Lev Barash

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Dynamical quantities with ALPS ED
by Mykola Maksymenko 13 Sep '12

13 Sep '12

Dear everybody, I am curious I it is possible to write a function in ALPS ED code to calculate the dynamical responses in a spectral representation ? It seems like in a simplest case one can compute it directly by having access to the matrix elements of the operator and corresponding energy eigenvalues of the Hamiltonian. Isn't it ? Will be thankful for the answer! With best regards, Mykola

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Binary installation of ALPS at an alternative location in windows
by Chao Shen 09 Sep '12

09 Sep '12

Hi all, I try to install ALPS binary in a position other than 'C:\program files' because there I would need administrator privilege to create files, etc. I noticed on ALPS website it says I just need to set environment variable ALPS_XML_DIR to point to the position of the actual XML directory, e.g. 'E:\ALPS\lib\xml'. However this doesn't really have any effect. When I run 'tutorial1a.py' which calls 'spinmc.exe' in the tutorial folder, 'spinmc.exe' complains about missing 'lattice.xml' at location 'C:\program files\ALPS\lib\xml'. Apparently the environment variable ALPS_XML_DIR didn't take effect at all. I am wondering if this is a bug or there are actually other environment variables to set? Thanks in advance. Yours, Chao

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Re: [ALPS-users] Comp-phys-alps-users Digest, Vol 77, Issue 5
by 陈巧妮 30 Aug '12

30 Aug '12

I'm calculating the one particle reduced density matrix, so it's the cdag_up:c_up, and cdag_down:c_down. 2012/8/30 <comp-phys-alps-users-request(a)lists.phys.ethz.ch> > Send Comp-phys-alps-users mailing list submissions to > comp-phys-alps-users(a)lists.phys.ethz.ch > > To subscribe or unsubscribe via the World Wide Web, visit > https://lists.phys.ethz.ch/listinfo/comp-phys-alps-users > or, via email, send a message with subject or body 'help' to > comp-phys-alps-users-request(a)lists.phys.ethz.ch > > You can reach the person managing the list at > comp-phys-alps-users-owner(a)lists.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. using sparsediag (???) > 2. Re: using sparsediag (Matthias Troyer) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Wed, 29 Aug 2012 21:35:13 -0400 > From: ??? <qiaoni2233(a)gmail.com> > To: comp-phys-alps-users(a)lists.phys.ethz.ch > Subject: [ALPS-users] using sparsediag > Message-ID: > <CAEM5Jm67=pHMzhVxKwZuPKFJjiNpw8A3+LSSa3hG0MJ9zEAC= > Q(a)mail.gmail.com> > Content-Type: text/plain; charset="iso-8859-1" > > Hi, everyone > I'm using sparsediag to get the ground state of Hubbard model, e.g. L=12, > with the particle number constraint Nup_total=6, Ndown_total=6. Using the > command line. If I calculate the correlation function , it takes 900 sec, > if not it takes 100 sec, does anyone know how to speed up this calculation? > > Btw if I use python to run the result, I can't see the result from the > task.out.xml file, how to look up the result > > -- > Qiaoni Chen > Department of Chemistry, > Princeton University > Princeton, NJ, 08544 > Tel +1-609-865-0817 >

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using sparsediag
by 陈巧妮 30 Aug '12

30 Aug '12

Hi, everyone I'm using sparsediag to get the ground state of Hubbard model, e.g. L=12, with the particle number constraint Nup_total=6, Ndown_total=6. Using the command line. If I calculate the correlation function , it takes 900 sec, if not it takes 100 sec, does anyone know how to speed up this calculation? Btw if I use python to run the result, I can't see the result from the task.out.xml file, how to look up the result -- Qiaoni Chen Department of Chemistry, Princeton University Princeton, NJ, 08544 Tel +1-609-865-0817

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