Conserve quantum number for composite unit cell
?Hello, I just wanted to ask if it is possible to preserve a combination of quantum numbers such as the total number of excitations: N = \sum_{bosonic sites} n_j + 1/2 \sum_{spinful sites} s_z and what the syntax for this would be? I guess that one option would be to define a new quantum number and let Splus raise it by 1/2 but I just thought that I would check this with you first! Otherwise, thank you for an excellent library! I have had no problems so far with the new release. Thanks, /Axel Gagge First year PhD Student, Stockholm University
I hope somebody else could give you a better answer, but I don’t think this is possible out of the box, and I’m not 100% sure it is at all possible in the way you think about it. What I would try is away to play around with a new model definition where you make a composite quantum number explicit. The "fermion Hubbard” and “alternative fermion Hubbard” could be of inspiration for how to conserve N and/or Sz instead of Nup and/or Ndown. Best, Michele -- ETH Zurich Dr. Michele Dolfi Institute for Theoretical Physics HIT G 32.4 Wolfgang-Pauli-Str. 27 8093 Zurich Switzerland dolfim@phys.ethz.ch www.itp.phys.ethz.ch +41 44 633 78 56 phone +41 44 633 11 15 fax
On Jan 17, 2017, at 4:10 PM, Axel Gagge <axel.gagge@fysik.su.se> wrote:
Hello, I just wanted to ask if it is possible to preserve a combination of quantum numbers such as the total number of excitations:
N = \sum_{bosonic sites} n_j + 1/2 \sum_{spinful sites} s_z
and what the syntax for this would be? I guess that one option would be to define a new quantum number and let Splus raise it by 1/2 but I just thought that I would check this with you first!
Otherwise, thank you for an excellent library! I have had no problems so far with the new release.
Thanks, /Axel Gagge First year PhD Student, Stockholm University
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You need to define a new combined quantum number, which is changed by the training and lowering operators for both types of particles.
On 17 Jan 2017, at 08:54, Michele Dolfi <dolfim@phys.ethz.ch> wrote:
I hope somebody else could give you a better answer, but I don’t think this is possible out of the box, and I’m not 100% sure it is at all possible in the way you think about it.
What I would try is away to play around with a new model definition where you make a composite quantum number explicit. The "fermion Hubbard” and “alternative fermion Hubbard” could be of inspiration for how to conserve N and/or Sz instead of Nup and/or Ndown.
Best, Michele
-- ETH Zurich Dr. Michele Dolfi Institute for Theoretical Physics HIT G 32.4 Wolfgang-Pauli-Str. 27 8093 Zurich Switzerland
dolfim@phys.ethz.ch <mailto:dolfim@phys.ethz.ch> www.itp.phys.ethz.ch <http://www.itp.phys.ethz.ch/>
+41 44 633 78 56 phone +41 44 633 11 15 fax
On Jan 17, 2017, at 4:10 PM, Axel Gagge <axel.gagge@fysik.su.se <mailto:axel.gagge@fysik.su.se>> wrote:
Hello, I just wanted to ask if it is possible to preserve a combination of quantum numbers such as the total number of excitations:
N = \sum_{bosonic sites} n_j + 1/2 \sum_{spinful sites} s_z
and what the syntax for this would be? I guess that one option would be to define a new quantum number and let Splus raise it by 1/2 but I just thought that I would check this with you first!
Otherwise, thank you for an excellent library! I have had no problems so far with the new release.
Thanks, /Axel Gagge First year PhD Student, Stockholm University
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?It wasn't very hard to define such a quantum number, but it seems like it actually makes the simulation run much slower. I suppose this is because another quantum number needs to be stored which leads to a larger basis size again? On the other hand, I can think of no way to properly define the spin operators without using the quantum numbers S, Sz... ? Many thanks, Axel ________________________________ Från: Comp-phys-alps-users <comp-phys-alps-users-bounces@lists.phys.ethz.ch> för Matthias Troyer <troyer@phys.ethz.ch> Skickat: den 17 januari 2017 19:42 Till: comp-phys-alps-users@lists.phys.ethz.ch Ämne: Re: [ALPS-users] Conserve quantum number for composite unit cell You need to define a new combined quantum number, which is changed by the training and lowering operators for both types of particles. On 17 Jan 2017, at 08:54, Michele Dolfi <dolfim@phys.ethz.ch<mailto:dolfim@phys.ethz.ch>> wrote: I hope somebody else could give you a better answer, but I don't think this is possible out of the box, and I'm not 100% sure it is at all possible in the way you think about it. What I would try is away to play around with a new model definition where you make a composite quantum number explicit. The "fermion Hubbard" and "alternative fermion Hubbard" could be of inspiration for how to conserve N and/or Sz instead of Nup and/or Ndown. Best, Michele -- ETH Zurich Dr. Michele Dolfi Institute for Theoretical Physics HIT G 32.4 Wolfgang-Pauli-Str. 27 8093 Zurich Switzerland dolfim@phys.ethz.ch<mailto:dolfim@phys.ethz.ch> www.itp.phys.ethz.ch<http://www.itp.phys.ethz.ch/> +41 44 633 78 56 phone +41 44 633 11 15 fax On Jan 17, 2017, at 4:10 PM, Axel Gagge <axel.gagge@fysik.su.se<mailto:axel.gagge@fysik.su.se>> wrote: ?Hello, I just wanted to ask if it is possible to preserve a combination of quantum numbers such as the total number of excitations: N = \sum_{bosonic sites} n_j + 1/2 \sum_{spinful sites} s_z and what the syntax for this would be? I guess that one option would be to define a new quantum number and let Splus raise it by 1/2 but I just thought that I would check this with you first! Otherwise, thank you for an excellent library! I have had no problems so far with the new release. Thanks, /Axel Gagge First year PhD Student, Stockholm University ---- Comp-phys-alps-users Mailing List for the ALPS Project http://alps.comp-phys.org/ List info: https://lists.phys.ethz.ch//listinfo/comp-phys-alps-users Archive: https://lists.phys.ethz.ch//pipermail/comp-phys-alps-users Unsubscribe by writing a mail to comp-phys-alps-users-leave@lists.phys.ethz.ch<mailto:comp-phys-alps-users-leave@lists.phys.ethz.ch>. ---- Comp-phys-alps-users Mailing List for the ALPS Project http://alps.comp-phys.org/ List info: https://lists.phys.ethz.ch//listinfo/comp-phys-alps-users Archive: https://lists.phys.ethz.ch//pipermail/comp-phys-alps-users Unsubscribe by writing a mail to comp-phys-alps-users-leave@lists.phys.ethz.ch.
Have you tried using a grandcanonical instead of fixing the quantum number?
On 18 Jan 2017, at 09:15, Axel Gagge <axel.gagge@fysik.su.se> wrote:
It wasn't very hard to define such a quantum number, but it seems like it actually makes the simulation run much slower. I suppose this is because another quantum number needs to be stored which leads to a larger basis size again? On the other hand, I can think of no way to properly define the spin operators without using the quantum numbers S, Sz...
Many thanks, Axel
Från: Comp-phys-alps-users <comp-phys-alps-users-bounces@lists.phys.ethz.ch <mailto:comp-phys-alps-users-bounces@lists.phys.ethz.ch>> för Matthias Troyer <troyer@phys.ethz.ch <mailto:troyer@phys.ethz.ch>> Skickat: den 17 januari 2017 19:42 Till: comp-phys-alps-users@lists.phys.ethz.ch <mailto:comp-phys-alps-users@lists.phys.ethz.ch> Ämne: Re: [ALPS-users] Conserve quantum number for composite unit cell
You need to define a new combined quantum number, which is changed by the training and lowering operators for both types of particles.
On 17 Jan 2017, at 08:54, Michele Dolfi <dolfim@phys.ethz.ch <mailto:dolfim@phys.ethz.ch>> wrote:
I hope somebody else could give you a better answer, but I don’t think this is possible out of the box, and I’m not 100% sure it is at all possible in the way you think about it.
What I would try is away to play around with a new model definition where you make a composite quantum number explicit. The "fermion Hubbard” and “alternative fermion Hubbard” could be of inspiration for how to conserve N and/or Sz instead of Nup and/or Ndown.
Best, Michele
-- ETH Zurich Dr. Michele Dolfi Institute for Theoretical Physics HIT G 32.4 Wolfgang-Pauli-Str. 27 8093 Zurich Switzerland
dolfim@phys.ethz.ch <mailto:dolfim@phys.ethz.ch> www.itp.phys.ethz.ch <http://www.itp.phys.ethz.ch/>
+41 44 633 78 56 phone +41 44 633 11 15 fax
On Jan 17, 2017, at 4:10 PM, Axel Gagge <axel.gagge@fysik.su.se <mailto:axel.gagge@fysik.su.se>> wrote:
Hello, I just wanted to ask if it is possible to preserve a combination of quantum numbers such as the total number of excitations:
N = \sum_{bosonic sites} n_j + 1/2 \sum_{spinful sites} s_z
and what the syntax for this would be? I guess that one option would be to define a new quantum number and let Splus raise it by 1/2 but I just thought that I would check this with you first!
Otherwise, thank you for an excellent library! I have had no problems so far with the new release.
Thanks, /Axel Gagge First year PhD Student, Stockholm University
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With extra quantum number, fixed n.o. excitations: runs in 124 s, E0, trunc_error = -1.0000000000001179, 0.00082901673330108058 With no extra quantum number, no fixed n.o. excitations (grand canonical...): runs in 24 s, E0, trunc_error = -0.99999999999997691, -1.3941131613197575e-16 I will proceed with the grand canonical and this is certainly enough, but is there some way around this slow-down? It would be nice to be able to conserve any charge which correspond to an abelian symmetry. Thanks, /Axel ________________________________ Från: Comp-phys-alps-users <comp-phys-alps-users-bounces@lists.phys.ethz.ch> för Matthias Troyer <troyer@phys.ethz.ch> Skickat: den 18 januari 2017 18:47 Till: comp-phys-alps-users@lists.phys.ethz.ch Ämne: Re: [ALPS-users] Conserve quantum number for composite unit cell Have you tried using a grandcanonical instead of fixing the quantum number? On 18 Jan 2017, at 09:15, Axel Gagge <axel.gagge@fysik.su.se<mailto:axel.gagge@fysik.su.se>> wrote: It wasn't very hard to define such a quantum number, but it seems like it actually makes the simulation run much slower. I suppose this is because another quantum number needs to be stored which leads to a larger basis size again? On the other hand, I can think of no way to properly define the spin operators without using the quantum numbers S, Sz... Many thanks, Axel ________________________________ Från: Comp-phys-alps-users <comp-phys-alps-users-bounces@lists.phys.ethz.ch<mailto:comp-phys-alps-users-bounces@lists.phys.ethz.ch>> för Matthias Troyer <troyer@phys.ethz.ch<mailto:troyer@phys.ethz.ch>> Skickat: den 17 januari 2017 19:42 Till: comp-phys-alps-users@lists.phys.ethz.ch<mailto:comp-phys-alps-users@lists.phys.ethz.ch> Ämne: Re: [ALPS-users] Conserve quantum number for composite unit cell You need to define a new combined quantum number, which is changed by the training and lowering operators for both types of particles. On 17 Jan 2017, at 08:54, Michele Dolfi <dolfim@phys.ethz.ch<mailto:dolfim@phys.ethz.ch>> wrote: I hope somebody else could give you a better answer, but I don’t think this is possible out of the box, and I’m not 100% sure it is at all possible in the way you think about it. What I would try is away to play around with a new model definition where you make a composite quantum number explicit. The "fermion Hubbard” and “alternative fermion Hubbard” could be of inspiration for how to conserve N and/or Sz instead of Nup and/or Ndown. Best, Michele -- ETH Zurich Dr. Michele Dolfi Institute for Theoretical Physics HIT G 32.4 Wolfgang-Pauli-Str. 27 8093 Zurich Switzerland dolfim@phys.ethz.ch<mailto:dolfim@phys.ethz.ch> www.itp.phys.ethz.ch<http://www.itp.phys.ethz.ch/> +41 44 633 78 56 phone +41 44 633 11 15 fax On Jan 17, 2017, at 4:10 PM, Axel Gagge <axel.gagge@fysik.su.se<mailto:axel.gagge@fysik.su.se>> wrote: Hello, I just wanted to ask if it is possible to preserve a combination of quantum numbers such as the total number of excitations: N = \sum_{bosonic sites} n_j + 1/2 \sum_{spinful sites} s_z and what the syntax for this would be? I guess that one option would be to define a new quantum number and let Splus raise it by 1/2 but I just thought that I would check this with you first! Otherwise, thank you for an excellent library! I have had no problems so far with the new release. Thanks, /Axel Gagge First year PhD Student, Stockholm University ---- Comp-phys-alps-users Mailing List for the ALPS Project http://alps.comp-phys.org/ List info: https://lists.phys.ethz.ch//listinfo/comp-phys-alps-users Archive: https://lists.phys.ethz.ch//pipermail/comp-phys-alps-users Unsubscribe by writing a mail to comp-phys-alps-users-leave@lists.phys.ethz.ch<mailto:comp-phys-alps-users-leave@lists.phys.ethz.ch>. ---- Comp-phys-alps-users Mailing List for the ALPS Project http://alps.comp-phys.org/ List info: https://lists.phys.ethz.ch//listinfo/comp-phys-alps-users Archive: https://lists.phys.ethz.ch//pipermail/comp-phys-alps-users Unsubscribe by writing a mail to comp-phys-alps-users-leave@lists.phys.ethz.ch<mailto:comp-phys-alps-users-leave@lists.phys.ethz.ch>. <my_models.xml><my_lattices.xml><Test of iDMRG.ipynb> ---- Comp-phys-alps-users Mailing List for the ALPS Project http://alps.comp-phys.org/ List info: https://lists.phys.ethz.ch//listinfo/comp-phys-alps-users Archive: https://lists.phys.ethz.ch//pipermail/comp-phys-alps-users Unsubscribe by writing a mail to comp-phys-alps-users-leave@lists.phys.ethz.ch<mailto:comp-phys-alps-users-leave@lists.phys.ethz.ch>.
I would suggest to use one quantum number for both Sz and N instead of two or three different quantum numbers.
On 18 Jan 2017, at 12:24, Axel Gagge <axel.gagge@fysik.su.se> wrote:
With extra quantum number, fixed n.o. excitations: runs in 124 s, E0, trunc_error = -1.0000000000001179, 0.00082901673330108058 With no extra quantum number, no fixed n.o. excitations (grand canonical...): runs in 24 s, E0, trunc_error = -0.99999999999997691, -1.3941131613197575e-16
I will proceed with the grand canonical and this is certainly enough, but is there some way around this slow-down? It would be nice to be able to conserve any charge which correspond to an abelian symmetry.
Thanks, /Axel
Från: Comp-phys-alps-users <comp-phys-alps-users-bounces@lists.phys.ethz.ch> för Matthias Troyer <troyer@phys.ethz.ch> Skickat: den 18 januari 2017 18:47 Till: comp-phys-alps-users@lists.phys.ethz.ch Ämne: Re: [ALPS-users] Conserve quantum number for composite unit cell
Have you tried using a grandcanonical instead of fixing the quantum number?
On 18 Jan 2017, at 09:15, Axel Gagge <axel.gagge@fysik.su.se> wrote:
It wasn't very hard to define such a quantum number, but it seems like it actually makes the simulation run much slower. I suppose this is because another quantum number needs to be stored which leads to a larger basis size again? On the other hand, I can think of no way to properly define the spin operators without using the quantum numbers S, Sz...
Many thanks, Axel
Från: Comp-phys-alps-users <comp-phys-alps-users-bounces@lists.phys.ethz.ch> för Matthias Troyer <troyer@phys.ethz.ch> Skickat: den 17 januari 2017 19:42 Till: comp-phys-alps-users@lists.phys.ethz.ch Ämne: Re: [ALPS-users] Conserve quantum number for composite unit cell
You need to define a new combined quantum number, which is changed by the training and lowering operators for both types of particles.
On 17 Jan 2017, at 08:54, Michele Dolfi <dolfim@phys.ethz.ch> wrote:
I hope somebody else could give you a better answer, but I don’t think this is possible out of the box, and I’m not 100% sure it is at all possible in the way you think about it.
What I would try is away to play around with a new model definition where you make a composite quantum number explicit. The "fermion Hubbard” and “alternative fermion Hubbard” could be of inspiration for how to conserve N and/or Sz instead of Nup and/or Ndown.
Best, Michele
-- ETH Zurich Dr. Michele Dolfi Institute for Theoretical Physics HIT G 32.4 Wolfgang-Pauli-Str. 27 8093 Zurich Switzerland
dolfim@phys.ethz.ch www.itp.phys.ethz.ch
+41 44 633 78 56 phone +41 44 633 11 15 fax
On Jan 17, 2017, at 4:10 PM, Axel Gagge <axel.gagge@fysik.su.se> wrote:
Hello, I just wanted to ask if it is possible to preserve a combination of quantum numbers such as the total number of excitations:
N = \sum_{bosonic sites} n_j + 1/2 \sum_{spinful sites} s_z
and what the syntax for this would be? I guess that one option would be to define a new quantum number and let Splus raise it by 1/2 but I just thought that I would check this with you first!
Otherwise, thank you for an excellent library! I have had no problems so far with the new release.
Thanks, /Axel Gagge First year PhD Student, Stockholm University
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participants (3)
-
Axel Gagge
-
Matthias Troyer
-
Michele Dolfi