Dear Michele. Thank you for your very detailed answer. I have one more question. I am afraid that the approaches you have listed in your male have only static nature. Maybe I am wrong but I didn't get how to apply t parameter depending on time. That maybe useful to simulate chain dynamics for example. Best, Nina
---------- Forwarded message ---------- From: comp-phys-alps-users-request@lists.phys.ethz.ch Date: 29 May 2014 12:00 Subject: Comp-phys-alps-users Digest, Vol 98, Issue 6 To: comp-phys-alps-users@lists.phys.ethz.ch
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Today's Topics:
1. Exploiting degeneracy in Hybridization impurity solver (backes@th.physik.uni-frankfurt.de) 2. Re: Exploiting degeneracy in Hybridization impurity solver (august@fzu.cz) 3. Re: Variational hopping parameter (Michele Dolfi)
----------------------------------------------------------------------
Message: 1 Date: Wed, 28 May 2014 12:40:54 +0200 From: backes@th.physik.uni-frankfurt.de To: comp-phys-alps-users@lists.phys.ethz.ch Subject: [ALPS-users] Exploiting degeneracy in Hybridization impurity solver Message-ID: < c3a4761d76660198b749e13b652541aa.squirrel@th.physik.uni-frankfurt.de> Content-Type: text/plain;charset=utf-8
Dear Alps developers,
is it possible to add an option for specifying and exploiting the degeneracy of some orbitals in the Hybridization expansion solver? E.g. for a paramagnetic calculation, where only half of the orbitals need to be measured (the input Hybridization function and interaction parameters are identical for these orbitals).
best regards, Steffen Backes
------------------------------
Message: 2 Date: Wed, 28 May 2014 14:57:49 +0200 From: august@fzu.cz To: comp-phys-alps-users@lists.phys.ethz.ch Subject: Re: [ALPS-users] Exploiting degeneracy in Hybridization impurity solver Message-ID: 63da888d9fd14d678d4270331e2a4696.squirrel@gate.fzu.cz Content-Type: text/plain;charset=utf-8
Hi Steffen,
Do you want just symmetrize the results for equivalent orbitals at the end of your calculation or really measure only on of the equivalent G. functions and ignore the rest? If I understand correctly, you dont gain anything by not measuring say down-spin orbitals in a paramagnetic system since the spin equivalence is broken during the simulation. Full measurement is therefore slower but leads to a better statistics.
Best regards,
Pavel
Dear Alps developers,
is it possible to add an option for specifying and exploiting the degeneracy of some orbitals in the Hybridization expansion solver? E.g. for a paramagnetic calculation, where only half of the orbitals need to be measured (the input Hybridization function and interaction parameters are identical for these orbitals).
best regards, Steffen Backes
------------------------------
Message: 3 Date: Wed, 28 May 2014 09:16:46 -0400 From: Michele Dolfi dolfim@phys.ethz.ch To: comp-phys-alps-users@lists.phys.ethz.ch Subject: Re: [ALPS-users] Variational hopping parameter Message-ID: C16EA761-87AF-4E04-B966-4F861E887659@phys.ethz.ch Content-Type: text/plain; charset="windows-1252"
Dear Nina,
In the latest release of ALPS 2.2.0b3 we introduced a new set of codes based on MPS. These codes use the ALPS model and lattice library, therefore there is not no problem running this kind of simulations.
To do so: 1. you need to create a custom lattice with a different type for each bond. https://alps.comp-phys.org/mediawiki/index.php/Tutorials:LatticeHOWTO
2. the model ?fermion Hubbard? is already able to handle different hopping amplitudes, just specify all values with the parameters t0=?, t1=?, ? where the number correspond to the bond type you specified in the lattice
3. finally you can setup a simulation using the new mps_evolve code. the easiest is to look at the mps-05 and mps-06 tutorials to have an idea on how to run the code.
Best regards, Michele
-- ETH Zurich 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 27 May 2014, at 18:30, Michael Wall mwall.physics@gmail.com wrote:
Dear Nina,
The TEBD code in ALPS is not set up for site-dependent Hubbard
parameters. Some of the other ALPS developers may be able to answer better whether such functionality will be added in near-term ALPS MPS codes. If not, Open Source MPS can perform the sorts of calculations you want to do, and eventually will become part of ALPS.
-Michael
On Fri, May 23, 2014 at 2:02 AM, bondnina bondnina@gmail.com wrote: Hi dear Alps users. I wonder is there any possibility to setup different hopping parameters
for each site in the Hubbard chain and evaluate such a system using TEBD technic.
Thank you for help.
-- Yours sincerely, Nina Bondarenko 1024R/EAC56154 9F6C DDF8 6873 5D19 FF9A 600E 46A4 42BE EAC5 6154
Hi,
For time dependent site dependent hopping you just need parameters as: t1[Time] = “0.1,0.15,0.2,..." t2[Time] = “0.5,0.45,0.4,..." …
An example of time dependent Hamiltonian parameters is in the tutorial mps-05-bhquench. For example, note that you additionally need to define COMPLEX=1 (to use complex numbers= and update_each=1 (to force the Hamiltonian to be generated at each time step.
Best regards, Michele
-- ETH Zurich 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 01 Jun 2014, at 14:16, bondnina bondnina@gmail.com wrote:
Dear Michele. Thank you for your very detailed answer. I have one more question. I am afraid that the approaches you have listed in your male have only static nature. Maybe I am wrong but I didn't get how to apply t parameter depending on time. That maybe useful to simulate chain dynamics for example. Best, Nina
Message: 3 Date: Wed, 28 May 2014 09:16:46 -0400 From: Michele Dolfi dolfim@phys.ethz.ch To: comp-phys-alps-users@lists.phys.ethz.ch Subject: Re: [ALPS-users] Variational hopping parameter Message-ID: C16EA761-87AF-4E04-B966-4F861E887659@phys.ethz.ch Content-Type: text/plain; charset="windows-1252"
Dear Nina,
In the latest release of ALPS 2.2.0b3 we introduced a new set of codes based on MPS. These codes use the ALPS model and lattice library, therefore there is not no problem running this kind of simulations.
To do so:
- you need to create a custom lattice with a different type for each bond.
https://alps.comp-phys.org/mediawiki/index.php/Tutorials:LatticeHOWTO
the model ?fermion Hubbard? is already able to handle different hopping amplitudes, just specify all values with the parameters t0=?, t1=?, ? where the number correspond to the bond type you specified in the lattice
finally you can setup a simulation using the new mps_evolve code. the easiest is to look at the mps-05 and mps-06 tutorials to have an idea on how to run the code.
Best regards, Michele
-- ETH Zurich 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 27 May 2014, at 18:30, Michael Wall mwall.physics@gmail.com wrote:
Dear Nina,
The TEBD code in ALPS is not set up for site-dependent Hubbard parameters. Some of the other ALPS developers may be able to answer better whether such functionality will be added in near-term ALPS MPS codes. If not, Open Source MPS can perform the sorts of calculations you want to do, and eventually will become part of ALPS.
-Michael
On Fri, May 23, 2014 at 2:02 AM, bondnina bondnina@gmail.com wrote: Hi dear Alps users. I wonder is there any possibility to setup different hopping parameters for each site in the Hubbard chain and evaluate such a system using TEBD technic. Thank you for help.
-- Yours sincerely, Nina Bondarenko 1024R/EAC56154 9F6C DDF8 6873 5D19 FF9A 600E 46A4 42BE EAC5 6154
-- Yours sincerely, Nina Bondarenko 1024R/EAC56154 9F6C DDF8 6873 5D19 FF9A 600E 46A4 42BE EAC5 6154
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