Comp-phys-alps-users

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1244 discussions

"fermionic" quantum numbers
by Cezary Sliwa 09 Jan '09

09 Jan '09

Hello, From http://alps.comp-phys.org/mediawiki-1.9.3/index.php/Tutorials:ModelHOWTO "Optionally, a type attribute can be set to bosonic (the default) or fermionic. It should be set to fermionic when the quantum number is a fermionic number operator. This information will be used when determining commutation relation between operators on different sites." This is very imprecise. To be honest, I do not understand that at all. First of all, good quantum numbers take numerical values, and numbers commute. Hence, the relations for quantum numbers are always *commutation* relations. The anticommutation relations are for the creation and annihilation *operators*. Hence, whether or not it make sense to assign such a "type=" attribute to a degree of freedom (call it a QUANTUMNUMBER), the attribute applies to *operators*! Moreover, not all operators, but only those that are odd in the creation and annihilation operators. For example, the spin operator for a pair of spin-up, spin-down fermion states satisfies *commutation* relations. Now please tell me why the code refuses to generate a matrix (probably for the hopping and exchange terms, but the error message does not state which terms pose a problem). Both terms are even in the creation and annihilation operators (capital S refers to a bosonic spin): <SITEBASIS name="orbital"> <QUANTUMNUMBER name="Nup" min="0" max="1" type="fermionic"/> <QUANTUMNUMBER name="Ndown" min="0" max="1" type="fermionic"/> <OPERATOR name="a_up" matrixelement="1"> <CHANGE quantumnumber="Nup" change="-1"/> </OPERATOR> <OPERATOR name="adag_up" matrixelement="1"> <CHANGE quantumnumber="Nup" change="1"/> </OPERATOR> <OPERATOR name="a_down" matrixelement="1"> <CHANGE quantumnumber="Ndown" change="-1"/> </OPERATOR> <OPERATOR name="adag_down" matrixelement="1"> <CHANGE quantumnumber="Ndown" change="1"/> </OPERATOR> <OPERATOR name="splus" matrixelement="1/2"> <CHANGE quantumnumber="Nup" change="1"/> <CHANGE quantumnumber="Ndown" change="-1"/> </OPERATOR> <OPERATOR name="sminus" matrixelement="1/2"> <CHANGE quantumnumber="Nup" change="-1"/> <CHANGE quantumnumber="Ndown" change="1"/> </OPERATOR> <OPERATOR name="sz" matrixelement="(Nup-Ndown)/2"/> <OPERATOR name="n" matrixelement="Nup+Ndown"/> </SITEBASIS> <BONDOPERATOR name="exchange_xy" source="x" target="y"> 1/2*(splus(x)*Sminus(y)+sminus(x)*Splus(y)) </BONDOPERATOR> <BONDOPERATOR name="exchange_z" source="x" target="y"> sz(x)*Sz(y) </BONDOPERATOR> <BONDOPERATOR name="hop" source="x" target="y"> adag_up(x)*a_up(y)+adag_up(y)*a_up(x)+adag_down(x)*a_down(y)+adag_down(y)*a_down(x) </BONDOPERATOR> Regards, Cezary Sliwa

2 11

Quantum heisenberg rectangular anti-fm lattice with random holes
by Brian Keith 08 Jan '09

08 Jan '09

I am endeavoring to create a rectangular QHAF lattice that has some of the magnetic sites "missing". Does anyone have any advice on how to go about creating a model that includes this randomness, these random, exchangeless holes in the lattice? thanks in advance, Brian

2 1

Magnetization for transverse Ising model
by Norbert Schuch 02 Jan '09

02 Jan '09

Hi, I am trying to compute the magnetization for the transverse field Ising model in 3D. If I understand correctly, I have to use Looper and place the field along X and the coupling along Z, i.e. what I do is LATTICE="simple cubic lattice" MODEL="spin" L=8 Jz=1 Jxy=0 T=0.1 THERMALIZATION=1000 SWEEPS=10000 REPRESENTATION="SSE" {Gamma=0;} {Gamma=1;} etc. The simulation works, however the magnetization is zero -- I assume this is because this is the magnetization in Z direction. What do I have to do in order to compute the magnetization along the transverse field? Thanks a lot, Norbert

1 0

Re: [ALPS-users] hamiltonian matrix
by Matthias Troyer 29 Dec '08

29 Dec '08

Look at the example/model directory in the ALPS libraries source trees. This is a program which prints the matrix for a model you specify. If you edit the file matrix.h you can also print all the states which gives you the matrix. Please be aware though that the ALPS exact diagonalization codes cannot do the biggest systems that you might be able to do using a matrix-free specialized code. What will you want to do after you checked your Mathematica code? Matthias On Dec 27, 2008, at 6:58 PM, khalid hassan wrote: > No I am using it for small systems. actually i made a code in > mathematica that calculates the hamiltonian matrix and basis > vectors, but it cannot be guaranteed 100% as i may have some > situations not obliged. Now my professor wants to check my code with > alps and then switch to alps. I dont know what next. for having the > matrix from the code I need to know the c++, for which i have to > spend some time as i know a little bit of c++ already. I want to > know that if I am on the right track. as I may spend 3 months on > learning c++ then i know that its not possible in alps. I am > thinking what freedom it will give me for calculating any > hamiltonian for any system. you said as it is possible now i can do > it with confidence. as my professor has given me this task, as i am > new in this field i dont know the reason. > > If you have some suggestion for me to have this without needing to > learn all c++ it will save my time as I am paying myself for my phd > program. > > Thanks to you for your answer. > > Best Regards > > Loane > > > --- On Sat, 12/27/08, Matthias Troyer <troyer(a)phys.ethz.ch> wrote: > >> From: Matthias Troyer <troyer(a)phys.ethz.ch> >> Subject: Re: [ALPS-users] hamiltonian matrix >> To: mkhloane(a)yahoo.com, comp-phys-alps-users(a)phys.ethz.ch >> Date: Saturday, December 27, 2008, 12:26 PM >> Look at the sparsediag or fulldiag code. You can print the >> basis and the matrix elements, but be warned that this can >> be a HUGE matrix. Why do you want to print it? >> >> Matthias >> >> On Dec 27, 2008, at 12:22 AM, khalid hassan wrote: >> >>> Dear all >>> >>> I am using the alps for a fermionic hubbard system. It >> gives the energies. I want the matrix elements of >> hamiltonian matrix. how can I have the hamiltonian matrix >> and basis states. >>> >>> Best Regards >>> Khalid Loane >>> >>> >>> >>> > > > > >

1 0

hamiltonian matrix
by khalid hassan 27 Dec '08

27 Dec '08

Dear all I am using the alps for a fermionic hubbard system. It gives the energies. I want the matrix elements of hamiltonian matrix. how can I have the hamiltonian matrix and basis states. Best Regards Khalid Loane

2 1

DMRG for Antiferromagnetic spin one half chain
by zhian asadzadeh 15 Dec '08

15 Dec '08

2 1

DMRG for Antiferromagnetic spin one half chain
by zhian asadzadeh 13 Dec '08

13 Dec '08

Hi Dears I have got following results:" for open boundary condition" SWEEP=8, MAXSTATES=400, L=200, E0= -0.44220777784 SWEEP=50, MAXSTATES=500, L=200, E0= -0.4422077778446504 SWEEP=8, MAXSTATES=150, L=600, E0= -0.442833001737 SWEEP=8, MAXSTATES= 500, L=600, E0=- 0.44283300822 SWEEP=8, MAXSTATES= 150, L=700, E0= -0.442877 We see that the result still have not got to -0.443147.maybe we increase the size ,getting to this energy but it takes a lot of time . for periodic boundary condition the energy that achieved is lower. I have a question. Are there some techniques for use of this algorithm such that, for example, for 100 or 200 sites we get to the desire energy? On Sun, Dec 7, 2008 at 6:00 AM, <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. DMRG For Antiferromagnetic spin one half chain (zhian asadzadeh) > 2. Re: DMRG For Antiferromagnetic spin one half chain > (Matthias Troyer) > 3. Re: DMRG For Antiferromagnetic spin one half chain > (Adrian E. Feiguin) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Sat, 6 Dec 2008 07:58:46 -0500 > From: "zhian asadzadeh" <zhian.asadzadeh(a)gmail.com> > Subject: [ALPS-users] DMRG For Antiferromagnetic spin one half chain > To: comp-phys-alps-users(a)phys.ethz.ch > Message-ID: > <89e5d6760812060458j27784855jaf87d27a63e2b4c1(a)mail.gmail.com> > Content-Type: text/plain; charset="iso-8859-1" > > Hi Dears > Thanks a lot. I have achieved the ground state energy as follow: > SWEEP=8, L=30,MAXSTATES=100, E0= -0.437045191. > SWEEP=8, L=50,MAXSTATES=140, E0= -0.43944220. > SWEEP=4, L=100,MAXSTATES=100, E0= -0.44127739. > SWEEP=4, L=100,MAXSTATES=300, E0= -0.44127739. > SWEEP=4, L=300,MAXSTATES=100, E0= -0.44127739. > The E0= -0.44127739 is the best enegy that i achieve and when i change the > sweep&M&L,the energy doesn't change.I can't improve the result ,also i > wrote > the model & lattice, but have not changed any thing. > Thanks. > > > > > > On Fri, Dec 5, 2008 at 6:00 AM, > <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. DMRG For Antiferromagnetic Spin one half chain (zhian asadzadeh) > > 2. Re: DMRG For Antiferromagnetic Spin one half chain > > (Matthias Troyer) > > 3. Re: DMRG For Antiferromagnetic Spin one half chain > > (Adrian E. Feiguin) > > > > > > ---------------------------------------------------------------------- > > > > Message: 1 > > Date: Thu, 4 Dec 2008 22:35:51 +0330 > > From: "zhian asadzadeh" <zhian.asadzadeh(a)gmail.com> > > Subject: [ALPS-users] DMRG For Antiferromagnetic Spin one half chain > > To: comp-phys-alps-users(a)phys.ethz.ch > > Message-ID: > > <89e5d6760812041105w5556998du756af1c79c8fb32b(a)mail.gmail.com> > > Content-Type: text/plain; charset="iso-8859-1" > > > > Hi Dear > > Thanks for your consideration.I run the program for different sizes and > > have > > increased it to 500 sites.For up to 100 site the result converges but it > is > > not the result that should it be (*0.443147*),the result that have > > achieved > > earlier from Bethe method and in the work of Mr.white that tests the DMRG > > for showing the powerful of this code. > > Thanks > > zhian > > > > > > On Wed, Dec 3, 2008 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. DMRG for antiferromagnetic spin one half chain (zhian asadzadeh) > > > 2. Re: DMRG for antiferromagnetic spin one half chain > > > (Matthias Troyer) > > > > > > > > > ---------------------------------------------------------------------- > > > > > > Message: 1 > > > Date: Tue, 2 Dec 2008 16:43:12 +0330 > > > From: "zhian asadzadeh" <zhian.asadzadeh(a)gmail.com> > > > Subject: [ALPS-users] DMRG for antiferromagnetic spin one half chain > > > To: comp-phys-alps-users(a)phys.ethz.ch > > > Message-ID: > > > <89e5d6760812020513q686feb0bge51a267945421f2(a)mail.gmail.com> > > > Content-Type: text/plain; charset="iso-8859-1" > > > > > > Hi ADRIAN > > > I run DMRG program for antiferromagnetic S=1/2 chain,but the result > that > > i > > > achieve for groun state energy doesn't concur with the result that > has > > > achieved from bethe ansats method (0.443147). > > > I have changed m&sweep& number of sites(to 1000 site) but my result > just > > 2 > > > digit concur with 0.443147. > > > I don't know what must i do. > > > I will be very appreciate if you can guide me. > > > > > > Thanks > > > zhian > > >

1 0

susceptibility
by Tadeusz Wasiutynski 09 Dec '08

09 Dec '08

Hello, What does it mean "susceptibility" or "uniform susceptibility" in classical tutorial? It is not (<M^2>-<|M|>^2)/T . regards Tadeusz -- Tadeusz Wasiutyński Institute of Nuclear Physics PAN Radzikowskiego 152 PL 31-342 Kraków tel. +48 12 662 8251

1 0

DMRG For Antiferromagnetic spin one half chain
by zhian asadzadeh 07 Dec '08

07 Dec '08

Hi Dears Thanks a lot. I have achieved the ground state energy as follow: SWEEP=8, L=30,MAXSTATES=100, E0= -0.437045191. SWEEP=8, L=50,MAXSTATES=140, E0= -0.43944220. SWEEP=4, L=100,MAXSTATES=100, E0= -0.44127739. SWEEP=4, L=100,MAXSTATES=300, E0= -0.44127739. SWEEP=4, L=300,MAXSTATES=100, E0= -0.44127739. The E0= -0.44127739 is the best enegy that i achieve and when i change the sweep&M&L,the energy doesn't change.I can't improve the result ,also i wrote the model & lattice, but have not changed any thing. Thanks. On Fri, Dec 5, 2008 at 6:00 AM, <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. DMRG For Antiferromagnetic Spin one half chain (zhian asadzadeh) > 2. Re: DMRG For Antiferromagnetic Spin one half chain > (Matthias Troyer) > 3. Re: DMRG For Antiferromagnetic Spin one half chain > (Adrian E. Feiguin) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Thu, 4 Dec 2008 22:35:51 +0330 > From: "zhian asadzadeh" <zhian.asadzadeh(a)gmail.com> > Subject: [ALPS-users] DMRG For Antiferromagnetic Spin one half chain > To: comp-phys-alps-users(a)phys.ethz.ch > Message-ID: > <89e5d6760812041105w5556998du756af1c79c8fb32b(a)mail.gmail.com> > Content-Type: text/plain; charset="iso-8859-1" > > Hi Dear > Thanks for your consideration.I run the program for different sizes and > have > increased it to 500 sites.For up to 100 site the result converges but it is > not the result that should it be (*0.443147*),the result that have > achieved > earlier from Bethe method and in the work of Mr.white that tests the DMRG > for showing the powerful of this code. > Thanks > zhian > > > On Wed, Dec 3, 2008 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. DMRG for antiferromagnetic spin one half chain (zhian asadzadeh) > > 2. Re: DMRG for antiferromagnetic spin one half chain > > (Matthias Troyer) > > > > > > ---------------------------------------------------------------------- > > > > Message: 1 > > Date: Tue, 2 Dec 2008 16:43:12 +0330 > > From: "zhian asadzadeh" <zhian.asadzadeh(a)gmail.com> > > Subject: [ALPS-users] DMRG for antiferromagnetic spin one half chain > > To: comp-phys-alps-users(a)phys.ethz.ch > > Message-ID: > > <89e5d6760812020513q686feb0bge51a267945421f2(a)mail.gmail.com> > > Content-Type: text/plain; charset="iso-8859-1" > > > > Hi ADRIAN > > I run DMRG program for antiferromagnetic S=1/2 chain,but the result that > i > > achieve for groun state energy doesn't concur with the result that has > > achieved from bethe ansats method (0.443147). > > I have changed m&sweep& number of sites(to 1000 site) but my result just > 2 > > digit concur with 0.443147. > > I don't know what must i do. > > I will be very appreciate if you can guide me. > > > > Thanks > > zhian > >

3 2

DMRG For Antiferromagnetic Spin one half chain
by zhian asadzadeh 04 Dec '08

04 Dec '08

Hi Dear Thanks for your consideration.I run the program for different sizes and have increased it to 500 sites.For up to 100 site the result converges but it is not the result that should it be (*0.443147*),the result that have achieved earlier from Bethe method and in the work of Mr.white that tests the DMRG for showing the powerful of this code. Thanks zhian On Wed, Dec 3, 2008 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. DMRG for antiferromagnetic spin one half chain (zhian asadzadeh) > 2. Re: DMRG for antiferromagnetic spin one half chain > (Matthias Troyer) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Tue, 2 Dec 2008 16:43:12 +0330 > From: "zhian asadzadeh" <zhian.asadzadeh(a)gmail.com> > Subject: [ALPS-users] DMRG for antiferromagnetic spin one half chain > To: comp-phys-alps-users(a)phys.ethz.ch > Message-ID: > <89e5d6760812020513q686feb0bge51a267945421f2(a)mail.gmail.com> > Content-Type: text/plain; charset="iso-8859-1" > > Hi ADRIAN > I run DMRG program for antiferromagnetic S=1/2 chain,but the result that i > achieve for groun state energy doesn't concur with the result that has > achieved from bethe ansats method (0.443147). > I have changed m&sweep& number of sites(to 1000 site) but my result just 2 > digit concur with 0.443147. > I don't know what must i do. > I will be very appreciate if you can guide me. > > Thanks > zhian >

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