Comp-phys-alps-users

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1244 discussions

Re: [ALPS-users] Comp-phys-alps-users Digest, Vol 61, Issue 2
by sunzhaoyu2000 12 Apr '11

12 Apr '11

Dear Matthias: Thank you very much for your reply. This random result is obtained by my DMRG code rather than ALPS. Do you mean that as parts of the Hamiltonian (H), all terms should be converged ? In fact, the term included in H is S1S2, thus S1S2=(SxSx+SySy+SzSz) acts as a whole in H. What I find is that: SxSx, SySy and SzSz are random, however, I think S1S2(=SxSx+SySy+SzSz) as a whole should have already be converged. I will check whether or not S1S2 is converged and present the result as soon as possible. Thank you again ! ------------------ Original ------------------ From: "comp-phys-alps-users-request"<comp-phys-alps-users-request(a)lists.phys.ethz.ch>; Date: Tue, Apr 12, 2011 06:00 PM To: "comp-phys-alps-users"<comp-phys-alps-users(a)lists.phys.ethz.ch>; Subject: Comp-phys-alps-users Digest, Vol 61, Issue 2 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. Would all the pairwise correlations be converged after the gound-state energy converges ? (???) 2. Re: Would all the pairwise correlations be converged after the gound-state energy converges ? (Matthias Troyer) ---------------------------------------------------------------------- Message: 1 Date: Tue, 12 Apr 2011 09:40:50 +0800 From: ??? <sunzhaoyu2000(a)gmail.com> Subject: [ALPS-users] Would all the pairwise correlations be converged after the gound-state energy converges ? To: comp-phys-alps-users(a)lists.phys.ethz.ch Message-ID: <BANLkTi=5kxfMAFzVhTNYK5i67CT=znarrQ(a)mail.gmail.com> Content-Type: text/plain; charset=ISO-8859-1 Dear ALPS users and developers: I want to study a spin ladder with four-site interaction. [ ? ?Phys. Rev. B 67, 100409(R) (2003), http://prb.aps.org/abstract/PRB/v67/i10/e100409 ? ? ] As ALPS 2.0 do not support 4-site terms, I code DMRG myself. For small size system(L=2,4,6,8,10) and the four-site interaction is zero, I have checked my DMRG code by comparing the obtained ground-state energy with that obtained by ED in ALPS. The two are fairly consistent. Then I move on to larger systems and four-body term are included. However, I am confused by the DMRG results: in the staggered dimer state of the system(see Phys. Rev. B 67, 100409(R) (2003), Fig. 2), when the ground-state of the ladder has converged, I check the two-site correlations, and find that the correlation function [ G_leg ] between nearest-neighboring two sites on the leg converges very well, meanwhile the correlation function [ G_rung ] between the two sites on the same rung does not converge at all ( G_rung seems to be random with the increase of size L, L = 100 ). I wonder is this a reasonable result ( is it possible that G_rung becomes undefined or because of some other physical reason, leading to a random average value for G_rung ) ? Or all the pairwise correlations in the system should always be converged after the gound-state energy converges ? Any suggestion would be appreciated. sunzhaoyu2000(a)gmail.com ------------------------------ Message: 2 Date: Tue, 12 Apr 2011 06:58:27 +0200 From: Matthias Troyer <troyer(a)phys.ethz.ch> Subject: Re: [ALPS-users] Would all the pairwise correlations be converged after the gound-state energy converges ? To: comp-phys-alps-users(a)lists.phys.ethz.ch Message-ID: <639622C3-988E-44CB-9E33-7329CC65A19F(a)phys.ethz.ch> Content-Type: text/plain; charset=utf-8 Hi, was this random result obtained by ALPS or by your code? Could you please send us the input files if it was with ALPS? Since the rung correlation function is actually part of the Hamiltonian I don't think that the energy is converged in your case. Matthias On 12 Apr 2011, at 03:40, ??? wrote: > Dear ALPS users and developers: > > I want to study a spin ladder with four-site interaction. > [ Phys. Rev. B 67, 100409(R) (2003), > http://prb.aps.org/abstract/PRB/v67/i10/e100409 ] > > As ALPS 2.0 do not support 4-site terms, I code DMRG myself. > For small size system(L=2,4,6,8,10) and the four-site interaction is zero, > I have checked my DMRG code by comparing the obtained ground-state > energy with that obtained by ED in ALPS. > The two are fairly consistent. > > Then I move on to larger systems and four-body term are included. > However, I am confused by the DMRG results: > in the staggered dimer state of the system(see Phys. Rev. B 67, > 100409(R) (2003), Fig. 2), > when the ground-state of the ladder has converged, > I check the two-site correlations, and find that > the correlation function [ G_leg ] between nearest-neighboring two > sites on the leg converges very well, > meanwhile the correlation function [ G_rung ] between the two sites on > the same rung does not converge at all > ( G_rung seems to be random with the increase of size L, L = 100 ). > > I wonder is this a reasonable result ( is it possible that G_rung > becomes undefined or because of some other physical reason, > leading to a random average value for G_rung ) ? > Or all the pairwise correlations in the system should always be > converged after the gound-state energy converges ? > Any suggestion would be appreciated. > > sunzhaoyu2000(a)gmail.com > End of Comp-phys-alps-users Digest, Vol 61, Issue 2 ***************************************************

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Re: [ALPS-users] Comp-phys-alps-users Digest, Vol 61, Issue 2
by 孙照宇 12 Apr '11

12 Apr '11

Dear Matthias: Thank you very much for your reply. This random result is obtained by my DMRG code rather than ALPS. Do you mean that all terms in the Hamiltonian (H) should be converged ? In fact, the term included in H is S1S2, thus S1S2=(SxSx+SySy+SzSz) acts as a whole in H. What I find is that: SxSx, SySy and SzSz are random, however, I think S1S2(=SxSx+SySy+SzSz) as a whole should have already be converged. I will check whether or not S1S2 is converged and present the result as soon as possible. Thank you again ! 2011/4/12 <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. Would all the pairwise correlations be converged after the > gound-state energy converges ? (???) > 2. Re: Would all the pairwise correlations be converged after > the gound-state energy converges ? (Matthias Troyer) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Tue, 12 Apr 2011 09:40:50 +0800 > From: ??? <sunzhaoyu2000(a)gmail.com> > Subject: [ALPS-users] Would all the pairwise correlations be converged > after the gound-state energy converges ? > To: comp-phys-alps-users(a)lists.phys.ethz.ch > Message-ID: <BANLkTi=5kxfMAFzVhTNYK5i67CT=znarrQ(a)mail.gmail.com> > Content-Type: text/plain; charset=ISO-8859-1 > > Dear ALPS users and developers: > > I want to study a spin ladder with four-site interaction. > [ ? ?Phys. Rev. B 67, 100409(R) (2003), > http://prb.aps.org/abstract/PRB/v67/i10/e100409 ? ? ] > > As ALPS 2.0 do not support 4-site terms, I code DMRG myself. > For small size system(L=2,4,6,8,10) and the four-site interaction is zero, > I have checked my DMRG code by comparing the obtained ground-state > energy with that obtained by ED in ALPS. > The two are fairly consistent. > > Then I move on to larger systems and four-body term are included. > However, I am confused by the DMRG results: > in the staggered dimer state of the system(see Phys. Rev. B 67, > 100409(R) (2003), Fig. 2), > when the ground-state of the ladder has converged, > I check the two-site correlations, and find that > the correlation function [ G_leg ] between nearest-neighboring two > sites on the leg converges very well, > meanwhile the correlation function [ G_rung ] between the two sites on > the same rung does not converge at all > ( G_rung seems to be random with the increase of size L, L = 100 ). > > I wonder is this a reasonable result ( is it possible that G_rung > becomes undefined or because of some other physical reason, > leading to a random average value for G_rung ) ? > Or all the pairwise correlations in the system should always be > converged after the gound-state energy converges ? > Any suggestion would be appreciated. > > sunzhaoyu2000(a)gmail.com > > > ------------------------------ > > Message: 2 > Date: Tue, 12 Apr 2011 06:58:27 +0200 > From: Matthias Troyer <troyer(a)phys.ethz.ch> > Subject: Re: [ALPS-users] Would all the pairwise correlations be > converged after the gound-state energy converges ? > To: comp-phys-alps-users(a)lists.phys.ethz.ch > Message-ID: <639622C3-988E-44CB-9E33-7329CC65A19F(a)phys.ethz.ch> > Content-Type: text/plain; charset=utf-8 > > Hi, > > was this random result obtained by ALPS or by your code? Could you please send us the input files if it was with ALPS? Since the rung correlation function is actually part of the Hamiltonian I don't think that the energy is converged in your case. > > Matthias > > On 12 Apr 2011, at 03:40, ??? wrote: > >> Dear ALPS users and developers: >> >> I want to study a spin ladder with four-site interaction. >> [ Phys. Rev. B 67, 100409(R) (2003), >> http://prb.aps.org/abstract/PRB/v67/i10/e100409 ] >> >> As ALPS 2.0 do not support 4-site terms, I code DMRG myself. >> For small size system(L=2,4,6,8,10) and the four-site interaction is zero, >> I have checked my DMRG code by comparing the obtained ground-state >> energy with that obtained by ED in ALPS. >> The two are fairly consistent. >> >> Then I move on to larger systems and four-body term are included. >> However, I am confused by the DMRG results: >> in the staggered dimer state of the system(see Phys. Rev. B 67, >> 100409(R) (2003), Fig. 2), >> when the ground-state of the ladder has converged, >> I check the two-site correlations, and find that >> the correlation function [ G_leg ] between nearest-neighboring two >> sites on the leg converges very well, >> meanwhile the correlation function [ G_rung ] between the two sites on >> the same rung does not converge at all >> ( G_rung seems to be random with the increase of size L, L = 100 ). >> >> I wonder is this a reasonable result ( is it possible that G_rung >> becomes undefined or because of some other physical reason, >> leading to a random average value for G_rung ) ? >> Or all the pairwise correlations in the system should always be >> converged after the gound-state energy converges ? >> Any suggestion would be appreciated. >> >> sunzhaoyu2000(a)gmail.com >> > > > > End of Comp-phys-alps-users Digest, Vol 61, Issue 2 > *************************************************** >

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Would all the pairwise correlations be converged after the gound-state energy converges ?
by 孙照宇 12 Apr '11

12 Apr '11

Dear ALPS users and developers: I want to study a spin ladder with four-site interaction. [ Phys. Rev. B 67, 100409(R) (2003), http://prb.aps.org/abstract/PRB/v67/i10/e100409 ] As ALPS 2.0 do not support 4-site terms, I code DMRG myself. For small size system(L=2,4,6,8,10) and the four-site interaction is zero, I have checked my DMRG code by comparing the obtained ground-state energy with that obtained by ED in ALPS. The two are fairly consistent. Then I move on to larger systems and four-body term are included. However, I am confused by the DMRG results: in the staggered dimer state of the system(see Phys. Rev. B 67, 100409(R) (2003), Fig. 2), when the ground-state of the ladder has converged, I check the two-site correlations, and find that the correlation function [ G_leg ] between nearest-neighboring two sites on the leg converges very well, meanwhile the correlation function [ G_rung ] between the two sites on the same rung does not converge at all ( G_rung seems to be random with the increase of size L, L = 100 ). I wonder is this a reasonable result ( is it possible that G_rung becomes undefined or because of some other physical reason, leading to a random average value for G_rung ) ? Or all the pairwise correlations in the system should always be converged after the gound-state energy converges ? Any suggestion would be appreciated. sunzhaoyu2000(a)gmail.com

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Re: [ALPS-users] [Alps-users] error in instaling alps
by Algis Garliauskas 07 Apr '11

07 Apr '11

> > All users, > I have installed Alps.1.3.5 and got to my mind the good results of > configuration bellow. But after make command it shows very many error. > What is wrong? I tried different boost options with prefix. Nothing changes > after 'make' the same errors > are repeating. Something is connected with private note: class version_type { private: typedef uint_least32_t base_type; base_type t; public: // should be private - but MPI fails if it's not!!! version_type(): t(0) {}; explicit version_type(const unsigned int & t_) : t(t_){ assert(t_ <= boost::integer_traits<base_type>::const_max); } or class class_id_type { private: typedef int_least16_t base_type; base_type t; public: // should be private - but then can't use BOOST_STRONG_TYPE below class_id_type() : t(0) {}; explicit class_id_type(const int t_) : t(t_){ assert(t_ <= boost::integer_traits<base_type>::const_max); } I can not edit: It is not possible! The boost prefix options doesn't influence to content of an archive file 'basic_archive.h', where almost all errors are appeared. See, about all in attached make results > Thanks for your advises in advance > Algis Garliauskas > > Summary of configuration: > ALPS version 1.3.5 > prefix /home/ag/ALPS > compiler type gnu [g++] > optimization yes > exceptions yes > warnings no > Boost version svn > MPI support no > OpenMP support no > HDF5 support no > LAPACK support no > SQLite support yes > XML parser native > Documentation no > ..---... > [ag@localhost ALPS]$ make > Making all in lib > make[1]: Entering directory `/ALPS/lib' > Making all in comm-sgl > make[2]: Entering directory `/ALPS/lib/comm-sgl' > /bin/sh ../../libtool --tag=CXX --mode=compile g++ -DHAVE_CONFIG_H > -I../../src -I../../src -DNDEBUG -g -O2 -MT buffer.lo -MD -MP > -MF .deps/buffer.Tpo -c -o buffer.lo `test -f > '../../src/alps/osiris/buffer.C' || echo > './'`../../src/alps/osiris/buffer.C > libtool: compile: g++ -DHAVE_CONFIG_H -I../../src -I../../src -DNDEBUG > -g -O2 -MT buffer.lo -MD -MP -MF .deps/buffer.Tpo > -c ../../src/alps/osiris/buffer.C -fPIC -DPIC -o .libs/buffer.o > In file included from ../../src/alps/osiris/dump.h:221:0, > from ../../src/alps/osiris/buffer.C:32: > /usr/include/boost/archive/basic_archive.hpp: In member function ‘void > alps::odump_archive::save_override(const boost::archive::version_type&, > int)’: > /usr/include/boost/archive/basic_archive.hpp:78:15: error: > ‘boost::archive::version_type::base_type > boost::archive::version_type::t’ is private > ../../src/alps/osiris/dumparchive.h:111:24: error: within this context > /usr/include/boost/archive/basic_archive.hpp: In member function ‘void > alps::odump_archive::save_override(const boost::archive::class_id_type&, > int)’: > /usr/include/boost/archive/basic_archive.hpp:111:15: error: > ‘boost::archive::class_id_type::base_type > boost::archive::class_id_type::t’ is private > ../../src/alps/osiris/dumparchive.h:117:29: error: within this context > /usr/include/boost/archive/basic_archive.hpp: In member function ‘void > alps::odump_archive::save_override(const > boost::archive::class_id_reference_type&, int)’: > /usr/include/boost/archive/basic_archive.hpp:111:15: error: > ‘boost::archive::class_id_type::base_type > boost::archive::class_id_type::t’ is private > ../../src/alps/osiris/dumparchive.h:123:29: error: within this context > /usr/include/boost/archive/basic_archive.hpp: In member function ‘void > alps::odump_archive::save_override(const > boost::archive::object_id_type&, int)’: > /usr/include/boost/archive/basic_archive.hpp:150:15: error: > ‘boost::archive::object_id_type::base_type > boost::archive::object_id_type::t’ is private > ../../src/alps/osiris/dumparchive.h:129:30: error: within this context > /usr/include/boost/archive/basic_archive.hpp: In member function ‘void > alps::odump_archive::save_override(const > boost::archive::object_reference_type&, int)’: > /usr/include/boost/archive/basic_archive.hpp:150:15: error: > ‘boost::archive::object_id_type::base_type > boost::archive::object_id_type::t’ is private > ../../src/alps/osiris/dumparchive.h:135:30: error: within this context > ../../src/alps/osiris/dumparchive.h: In member function ‘void > alps::idump_archive::load_override(boost::archive::class_id_reference_type&, > int)’: > ../../src/alps/osiris/dumparchive.h:238:54: error: no matching function > for call to > > ‘boost::archive::class_id_reference_type::class_id_reference_type(int_least16_t&)’ > /usr/include/boost/archive/basic_archive.hpp:261:73: note: candidates > are: > > boost::archive::class_id_reference_type::class_id_reference_type(boost::archive::class_id_type) > /usr/include/boost/archive/basic_archive.hpp:261:54: note: > boost::archive::class_id_reference_type::class_id_reference_type(const > boost::archive::class_id_reference_type&) > ../../src/alps/osiris/dumparchive.h: In member function ‘void > alps::idump_archive::load_override(boost::archive::object_reference_type&, > int)’: > ../../src/alps/osiris/dumparchive.h:252:52: error: no matching function > for call to > > ‘boost::archive::object_reference_type::object_reference_type(uint_least32_t&)’ > /usr/include/boost/archive/basic_archive.hpp:263:72: note: candidates > are: > > boost::archive::object_reference_type::object_reference_type(boost::archive::object_id_type) > /usr/include/boost/archive/basic_archive.hpp:263:53: note: > boost::archive::object_reference_type::object_reference_type(const > boost::archive::object_reference_type&) > make[2]: *** [buffer.lo] Error 1 > make[2]: Leaving directory `/ALPS/lib/comm-sgl' > make[1]: *** [all-recursive] Error 1 > make[1]: Leaving directory `/ALPS/lib' > make: *** [all-recursive] Error 1 > > > > -- Algis Garliauskas Prof., Hab. dr. Vilnius University Institute of Mathematics & Informatics Akademijos 4, LT-6883, Vilnius, Lithuania Tel.:370 5 2109333

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alps scheduler, histogram observable
by Sebastian Huber 29 Mar '11

29 Mar '11

Dear all, I am using the alea libraries for an implementation of a monte carlo simulation. If I try to use the HistogramObservable as follows: measurements << alps::HistogramObservable<double>("MyObservable"); It compiles, it runs, but when it tries to write the hdf5 file either while checkpointing or when finished I get the following error: HDF5 Error writing path '/' on type 'N4alps9scheduler12MCSimulationE': HDF5 Error writing path '/simulation/results' on type 'N4alps13ObservableSetE': HDF5 Error writing path 'MyObservable' on type 'N4alps19HistogramObservableIdEE': HDF5 Error writing path '@size' on type 'j': Error in /Users/sebi/ALPS/include/alps/hdf5.hpp on 842 in set_attribute: unknown path: /simulation/results/MyObservable Regards, Sebastian -- Sebastian Huber Department of Condensed Matter Physics The Weizmann Institute of Science 76100 Rehovot Web: http://www.weizmann.ac.il/~huber Tel: +972 8 934 4258

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"exit status=265" ?
by Chen Ahai 28 Mar '11

28 Mar '11

dear all, The DMRG program is exit and get “exit status=265” when I calculate the correlation function with more than 40 sweeps and 400 maxstates on a cluster with PBS. Enough memory is offered here (more than 20G). I have no idea about this return.....is anyone know about this problem? thank you very much ! chenahai -- -------------------------------------------------------------------------- Chen Ahai Department of Physics, Zhejiang Normal University Jinhua, Zhejiang Province, 321004, China e-mail: chenahaiphysics(a)gmail.com; chenahai(a)yahoo.cn

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multiple eigenvalues (degenerate eigenstates) in sparsediag
by Andriy Zhugayevych 25 Mar '11

25 Mar '11

For a system with multiple eigenvalues (e.g. ground state of the extended Hubbard model on a closed chain of 4 sites with 4 electrons, zero spin, and U=2V) sparsediag program returns only one eigenstate for each multiplet. How other eigenstates can be obtained if there is no quantum number differentiating them? Thanks, Andriy

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Re: [ALPS-users] How to define an operator A in "models.xml"
by 孙照宇 25 Mar '11

25 Mar '11

Dear Matthias, Thank you very much for your reply. I have solved the problem with my own DMRG code. However, I will keep tracking ALPS project. It is indeed very great. Thank you for your work. 2011/3/25 <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. Re: How to define an operator A in "models.xml" (Matthias Troyer) > 2. multiple eigenvalues (degenerate eigenstates) in sparsediag > (Andriy Zhugayevych) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Thu, 24 Mar 2011 12:28:28 -0500 > From: Matthias Troyer <troyer(a)phys.ethz.ch> > Subject: Re: [ALPS-users] How to define an operator A in "models.xml" > To: comp-phys-alps-users(a)lists.phys.ethz.ch > Message-ID: <DAC79DA4-5BC5-49DA-BAAE-1B885B6736BB(a)phys.ethz.ch> > Content-Type: text/plain; charset="utf-8" > > Dear Sunzhaoyu, > > This is not implemented yet. For now you will have to decompose it into > more elementary operators. > > Matthias > > On Mar 18, 2011, at 12:38 AM, ??? wrote: > > > Dear ALPS users and developers > > > > I want to re-produce the result of a 12x2 spin ladder with four-site > interaction. > > The four-site interaction is between two nearest-neighboring rungs. > > Please see: > > [ Phys. Rev. B 74, 155119 (2006), > http://prb.aps.org/abstract/PRB/v74/i15/e155119 ] > > > > > > However, it seems that ALPS 2.0 do not support 4-site terms. > > Thus I define every rung as a single site, > > then the ladder becomes a one-dimensional chain (local degree of freedom > is 4), > > and the four-site interaction becomes a two-site interaction. > > > > In original ladder, the SITEBASIS is just {sz} = {-1/2, 1/2}. > > In this basis operators such as Sminus have very compact expressions > > thus they can be simply define as: > > <OPERATOR name="Sminus" matrixelement="sqrt(S*(S+1)-Sz*(Sz-1))"> > > > > > > However, in the new model, a possible choice of SITEBASIS is {J,Jz}={00, > 1-1, 10, 11}. > > In this new basis, operators do not have very compact expressions, > > however, the elements of the operator can be easily obtained through > unitary transformation. > > The problem is, I can figure out all the elements of an operator in > basis{J, Jz}, but I do not know how to define the operator in "models.xml". > > > > In other words, > > suppose an operator X in basis {J, Jz} is explicitly found to be > > [ 1, 0, 0, 0 > > 0, 2, 1, 0 > > 0, 1, 3, 0 > > 0, 0, 0, 4] > > then in ALPS 2.0, is it possible to define X by simply writing down every > elements Xij in "models.xml" ? > > > > Any suggestion would be appreciated. > > > > > > sunzhaoyu > > > > > > > > > > > > > > > > > > > >

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How to define an operator A in "models.xml"
by 孙照宇 24 Mar '11

24 Mar '11

Dear ALPS users and developers I want to re-produce the result of a 12x2 spin ladder with four-site interaction. The four-site interaction is between two nearest-neighboring rungs. Please see: [ Phys. Rev. B 74, 155119 (2006), http://prb.aps.org/abstract/PRB/v74/i15/e155119 ] However, it seems that ALPS 2.0 do not support 4-site terms. Thus I define every rung as a single site, then the ladder becomes a one-dimensional chain (local degree of freedom is 4), and the four-site interaction becomes a two-site interaction. In original ladder, the SITEBASIS is just {sz} = {-1/2, 1/2}. In this basis operators such as Sminus have very compact expressions thus they can be simply define as: <OPERATOR name="Sminus" matrixelement="sqrt(S*(S+1)-Sz*(Sz-1))"> However, in the new model, a possible choice of SITEBASIS is {J,Jz}={00, 1-1, 10, 11}. In this new basis, operators do not have very compact expressions, however, the elements of the operator can be easily obtained through unitary transformation. The problem is, I can figure out all the elements of an operator in basis{J, Jz}, but I do not know how to define the operator in "models.xml". In other words, suppose an operator X in basis {J, Jz} is explicitly found to be [ 1, 0, 0, 0 0, 2, 1, 0 0, 1, 3, 0 0, 0, 0, 4] then in ALPS 2.0, is it possible to define X by simply writing down every elements Xij in "models.xml" ? Any suggestion would be appreciated. sunzhaoyu

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Bose Hubbard and DMRG
by "Michał Maik" 23 Mar '11

23 Mar '11

Hi I was wondering if DMRG works with the boson Hubbard model? I tried making a parameter file for a 1D open chain lattice with filling factor of one and the DMRG routine wouldn't work. Are there certain parameter restrictions that must be put into place for it to work? Thanks Regards Michal Maik

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