Hi all,
I'm new to ALPS, but before I try to learn how to use it, I wanted to resolve an ambiguity in the documentation to figure out whether it's applicable to my problem. I want to find the magnetic susceptibility for a spin system, where the magnetic field h couples to Sz_tot as usual. However, I wish to use a Hamiltonian that does not commute with Sz_tot, hence does not leave it conserved.
In the fulldiag "documentation" file http://alps.comp-phys.org/mediawiki/index.php/Documentation:FullDiagonalizat... there is a red warning claiming that I cannot use fulldiag if Sz_tot is not conserved. However, this documentation looks like it's two years old.
The new tutorial, at http://alps.comp-phys.org/mediawiki/index.php/ALPS_2_Tutorials:ED-06_FullDia... has no such warning, but it only gives an example for calculating the susceptibility for a Heisenberg Hamiltonian, which conserves Sz_tot.
Do you know if I can use fulldiag (or anything else) if my Sz_tot is not conserved?
Thanks!
Itamar
On Nov 24, 2010, at 8:50 AM, Itamar Kimchi wrote:
Hi all,
I'm new to ALPS, but before I try to learn how to use it, I wanted to resolve an ambiguity in the documentation to figure out whether it's applicable to my problem. I want to find the magnetic susceptibility for a spin system, where the magnetic field h couples to Sz_tot as usual. However, I wish to use a Hamiltonian that does not commute with Sz_tot, hence does not leave it conserved.
In the fulldiag "documentation" file http://alps.comp-phys.org/mediawiki/index.php/Documentation:FullDiagonalizat... there is a red warning claiming that I cannot use fulldiag if Sz_tot is not conserved. However, this documentation looks like it's two years old.
The new tutorial, at http://alps.comp-phys.org/mediawiki/index.php/ALPS_2_Tutorials:ED-06_FullDia... has no such warning, but it only gives an example for calculating the susceptibility for a Heisenberg Hamiltonian, which conserves Sz_tot.
Do you know if I can use fulldiag (or anything else) if my Sz_tot is not conserved?
Fulldiag can be used but you cannot use the evaluation tools to automatically make plots as a function of the field. Instead you have to run one simulation per value of the field.
Matthias
Great, thank you for such a quick response!
On Tue, Nov 23, 2010 at 11:55 PM, Matthias Troyer troyer@phys.ethz.ch wrote:
On Nov 24, 2010, at 8:50 AM, Itamar Kimchi wrote:
Hi all,
I'm new to ALPS, but before I try to learn how to use it, I wanted to resolve an ambiguity in the documentation to figure out whether it's applicable to my problem. I want to find the magnetic susceptibility for a spin system, where the magnetic field h couples to Sz_tot as usual. However, I wish to use a Hamiltonian that does not commute with Sz_tot, hence does not leave it conserved.
In the fulldiag "documentation" file http://alps.comp-phys.org/mediawiki/index.php/Documentation:FullDiagonalizat... there is a red warning claiming that I cannot use fulldiag if Sz_tot is not conserved. However, this documentation looks like it's two years old.
The new tutorial, at http://alps.comp-phys.org/mediawiki/index.php/ALPS_2_Tutorials:ED-06_FullDia... has no such warning, but it only gives an example for calculating the susceptibility for a Heisenberg Hamiltonian, which conserves Sz_tot.
Do you know if I can use fulldiag (or anything else) if my Sz_tot is not conserved?
Fulldiag can be used but you cannot use the evaluation tools to automatically make plots as a function of the field. Instead you have to run one simulation per value of the field.
Matthias
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