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models in classical monte carlo simulation
by GANG CHEN 19 Sep '07

19 Sep '07

Hi all, What is the default libary for the model in classical monte carlo simulation? In the tutorial there are Heisenberg model and Ising model which could not be found in the file lib/xml/models.xml. Could I define my own models as usual way? And do I refer the model libary in the parameter file also in the same way as sparsediagonalization? Thanks, Gang

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could you help look at these two definitions
by Gang Chen 18 Sep '07

18 Sep '07

Hi all, sorry to bother, I have some trouble with the parameter definition in my models Hamiltonian. Could someone help look at the "BONDTERM" and particularly the specification of parameter? In the examples in the tutorials, I saw that another set of parameters is defined in every type of bondterm, and the default values of these parameters are referred the parameters defined in the beginning. Because my model Hamiltonian is the Heisenberg's model with Dzyaloshinski-Moriya interaction, so I didn't introduce new parameters for each bond (named as J#), and simply use the parameters defined in the beginning. Can I do this? Is my definition correct? If there is something wrong in the lattice and model definition, could you help correct them? Thanks a lot. Gang

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Question about DMRG
by Justin David Peel 16 Sep '07

16 Sep '07

Hi all, I didn't get an answer when I asked before about this, but I thought that I would try again. In DMRG the common practice is to use the truncation errors at different MAXSTATES to extrapolate the energy. However, the dmrg code currently does not write out the truncation error to a file. Is there a way to have the dmrg program write this out for the last sweep? Even just one value from the last sweep or the mean would be useful. I know that the truncation error for each step is written out to the screen, but it is rather inefficient to run one batch at a time and then copy down the truncation error. I really appreciate the help that I have received thus far and am very grateful for the ALPS collaboration overall. I'd appreciate any hints you might have regarding this. Thanks, Justin Peel

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Re: [ALPS-users] ALPS
by Matthias Troyer 12 Sep '07

12 Sep '07

On 12 Sep 2007, at 18:05, Amit Choubey wrote: > Respected Sir, > > I am Amit Choubey, MSc student of IIT Kharagpur, India. I am trying > to solve Fermionic Hubbard Model using ALPS. But I am not able to > understand how should I define the creation and annhiliation > operator for fermions. Its because they follow an anticommutation > relationship and the eigenvalues are dependent on the particular > arrangement of the fermions. Please help me in this regard. An > example describing this will be really nice of you. > > Thanking You. > > Sincerely, > Amit Choubey Just look at the models.xml file in ALPS for some examples Matthias

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2 questions
by GANG CHEN 08 Sep '07

08 Sep '07

Hi, all, I have two questions to bother you. the first one is: Here is part of the model I defined. It is Heisenberg AFM model with different coupling constant J on each type of bond. See the defined BONDTERM. The default coupling Jz2 is J, and I specify J=1 in the parameter file. <HAMILTONIAN name="spin"> <PARAMETER name="Jz" default="J"/> <PARAMETER name="Jxy" default="J"/> <PARAMETER name="J" default="1"/> <BONDTERM type="2" source="i" target="j"> <PARAMETER name="Jz2" default="J"/> <PARAMETER name="Jxy2" default="J"/> Jz2*Sz(i)*Sz(j)+Jxy2*exchange_xy(i,j)+ ........ However, when I tried to run it, I got following error message. parsing task files ... Starting task 1. Cannot evaluate expression Jz2 * -0.5 * -0.5 It seems that Alps didn't take the numerical value of Jz2. Or I make a mistake somewhere. Can someone help point out? The second question about "sparse diagonalization": When I use Lanczos method to get the ground state energy, it seems that it can only give me the value of energy, not the degeneracy of states. The value of energy has error in it, as a result, sometimes, it will consider two degenerate states as two different states. Is my understanding correct? So, in order to judge whether the two states are degenerate or not from the energy value, we need to estimate of the magnitude of errors. Do you know how to do it? Run the same program several time and see the fluctuation of the corresponding energy and state? What do you suggest? best, Gang

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ALPS Lib install Q ?
by Elham Noor Ghasemi 03 Sep '07

03 Sep '07

Hi Dear Support / Develop Team Thanks first of all to read my e-mail. I was trying to install ALPS library ver 1.2.2 in windows. After all instructions in installation page and installing cygwin with required packages I dealt with an error after running make instrauction. The followings are what I saw as output of instruction. I will be very appreciated if you could help me WHAT IS THE PROBLEM? Thanks in advance Sincerely Elham Noor Ghasemi Isfahan University of Technology - Physics Departments Dell@dell-5c859b3361 /home/alps-1.2.2 $ make && make install Making all in lib make[1]: Entering directory `/home/alps-1.2.2/lib' Making all in alps make[2]: Entering directory `/home/alps-1.2.2/lib/alps' if /bin/sh ../../libtool --mode=compile g++ -DHAVE_CONFIG_H -I../../src -I../../ src -DNDEBUG -I/usr/include/boost-1_33_1 -DNDEBUG -pthread -w -ftemplate-dep th-150 -O3 -fexceptions -MT parameterlist.lo -MD -MP -MF ".deps/parameterlist.Tp o" -c -o parameterlist.lo `test -f '../../src/alps/parameterlist.C' || echo './' `../../src/alps/parameterlist.C; \ then mv -f ".deps/parameterlist.Tpo" ".deps/parameterlist.Plo"; else rm -f ".deps/parameterlist.Tpo"; exit 1; fi g++ -DHAVE_CONFIG_H -I../../src -I../../src -DNDEBUG -I/usr/include/boost-1_33_ 1 -DNDEBUG -pthread -w -ftemplate-depth-150 -O3 -fexceptions -MT parameterlist.l o -MD -MP -MF .deps/parameterlist.Tpo -c ../../src/alps/parameterlist.C -DPIC g++: unrecognized option `-pthread' In file included from ../../src/alps/osiris.h:35, from ../../src/alps/parameters.h:34, from ../../src/alps/parameterlist.h:35, from ../../src/alps/parameterlist.C:31: ../../src/alps/osiris/xdrdump.h:41:21: rpc/rpc.h: No such file or directory In file included from ../../src/alps/osiris.h:35, from ../../src/alps/parameters.h:34, from ../../src/alps/parameterlist.h:35, from ../../src/alps/parameterlist.C:31: ../../src/alps/osiris/xdrdump.h:95: error: `XDR' does not name a type ../../src/alps/osiris/xdrdump.h:140: error: `XDR' does not name a type make[2]: *** [parameterlist.lo] Error 1 make[2]: Leaving directory `/home/alps-1.2.2/lib/alps' make[1]: *** [all-recursive] Error 1 make[1]: Leaving directory `/home/alps-1.2.2/lib' make: *** [all-recursive] Error 1 Dell@dell-5c859b3361 /home/alps-1.2.2 $

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one question about complex parameter
by GANG CHEN 28 Aug '07

28 Aug '07

Hi, all The site operators for spin are defined as S+, S- and Sz in ALPS, in order to express Sy, we need to introduce "i". Now I have a spin Hamiltonian, if I express it in terms of S+, S- and Sz, there will be "i" terms in the Hamiltonian. In such case, how do I specify each term or parameters? Thanks, GANG CHEN

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two questions
by GANG CHEN 23 Aug '07

23 Aug '07

Hi all, In the lattice I am working on, there are N (N>2) equivalent sites in primitive unit cell. All the bonds are equivalent, but have different orientation. e.g. kagome lattice, the three bonds have different directions. Now I need to write down the Dzyloshiski-Moriya interaction for this lattice, the D vector depends on the direction of the bond, or more specifically, D vector depends on the relative coordinates of the two sites. My question is how to specify the bond operator for different bonds, or, how to specify the coordinate-dependence of the bond operators? The second question is about how to specify unit cell of the lattice. Here are two concrete examples from the library. I think if i can understand them, i won't have trouble with my lattice. 1. triangular, <UNITCELL name="triangular" dimension="2"> <VERTEX/> <EDGE><SOURCE vertex="1" offset="0 0"/><TARGET vertex="1" offset="0 1"/></EDGE> <EDGE><SOURCE vertex="1" offset="0 0"/><TARGET vertex="1" offset="1 0"/></EDGE> <EDGE><SOURCE vertex="1" offset="0 0"/><TARGET vertex="1" offset="-1 1"/></EDGE> </UNITCELL> I am confused about this. I don't why it is specified as this. It doesn't seem natural to me. Just from the offset, it will form a right triangle, rather than an equilateral triangle. Also, does the length of the offset matter? 2, kagome, <UNITCELL name="Kagome" dimension="2"> <VERTEX><COORDINATE>0 0</COORDINATE></VERTEX> <VERTEX><COORDINATE>0.5 0</COORDINATE></VERTEX> <VERTEX><COORDINATE>0 0.5</COORDINATE></VERTEX> <EDGE><SOURCE vertex="1"/><TARGET vertex="2"/></EDGE> <EDGE><SOURCE vertex="1"/><TARGET vertex="3"/></EDGE> <EDGE><SOURCE vertex="2"/><TARGET vertex="3"/></EDGE> <EDGE><SOURCE vertex="1"/><TARGET vertex="2" offset="-1 0"/></EDGE> <EDGE><SOURCE vertex="2"/><TARGET vertex="3" offset="1 -1"/></EDGE> <EDGE><SOURCE vertex="1"/><TARGET vertex="3" offset="0 -1"/></EDGE> </UNITCELL> Why specify the coordinates as this? Why rewrite the <EDGE> once more with offset? I cannot draw a unit cell from just looking this. Could some one explain this for me? THanks very much! Gang Chen

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A couple of questions more
by Justin David Peel 15 Aug '07

15 Aug '07

Hi all, Thanks for all of the help so far. I just have a couple more questions. First of all, is there a way to set a parameter to infinity? I'm not talking about the lattice size, but for instance in the Hubbard model, I would like to try setting U to infinity or at least very large. I can't set it much larger than 17000 without the program messing up. The second question I have is a little more involved. I would like to set up an open chain lattice as defined in the standard library, but with a different 'type' for each site. Actually, what I would like is for the sites to alternate between two different types. I have read all of the docs that I could find, but haven't been able to get this to work yet. I tried changing the unit cell, among other things, but when I tried out my model, it didn't work how it should with the same U's everywhere (in the Hubbard model). If anyone can help me out with this, I would really appreciate this. Thanks again for all of your kind help, Justin

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Hubbard model DMRG questions
by Justin David Peel 09 Aug '07

09 Aug '07

Hello, I have a few questions and a few suggestions. So far on my first day of using ALPS, I think that it is amazingly powerful and would like to say thank you for all of the work you all have done. I have been studying DMRG by myself making my own codes, but they are fairly simple compared to this. I have figured out the basics of the Heisenberg model with the help of the tutorials and obtained the Haldane gap, but I want to make sure that I am doing the fermionic Hubbard model correctly. Here is the parameter file I am using: LATTICE="open chain lattice" SWEEPS=4 MAXSTATES=100 { MODEL="fermion Hubbard", L=8, N_total=8, U=10 } Is this correct for a simple calculation of the ground state? Also, I was looking through the Models tutorial and noticed under the "Hamiltonian descriptions" subtopic that the SITETERM has a type. Does the type correspond to a given site that it applies to? For instance, could I set the first site to have a repulsion term of U and the second term to have a repulsion term of 2*U and so on? If not, is there a way to do this? As far as suggestions, I had to figure some things out when installing under Windows/Cygwin and thought that I could offer some modifications to the installation instructions. The biggest obstacle was setting the $PATH to include the binaries folder in the Installation folder. I can give some other suggested changes regarding if they are wanted. I also noticed that the particle in a box demo wasn't working for me. (The error message using parm1 in the tutorials folder is "EXCEPTION: bad lexical cast: source type value could not be interpreted as target" when following the instructions of the tutorial page) Lastly, I was wondering if the links could be made to work for the user workshop page if the files exist. I think they would be a great help. Thank you for your efforts and for any help you can offer, Justin Peel

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