quantum XY model with an uniform magnetic field in the x-direction
Hi ALPS users I was wondering can one use looper to simulate quantum XY model with an uniform magnetic field in the x-direction. Thanks.
With ferromagnetic or antiferromagnetic couplings? On Jan 13, 2011, at 11:33 AM, Kubila wrote:
Hi ALPS users
I was wondering can one use looper to simulate quantum XY model with an uniform magnetic field in the x-direction. Thanks.
Hi Prof. Troyer With antiferromagnetic couplings. --- On Thu, 1/13/11, Matthias Troyer <troyer@phys.ethz.ch> wrote: From: Matthias Troyer <troyer@phys.ethz.ch> Subject: Re: [ALPS-users] quantum XY model with an uniform magnetic field in the x-direction To: comp-phys-alps-users@lists.phys.ethz.ch Date: Thursday, January 13, 2011, 2:44 AM With ferromagnetic or antiferromagnetic couplings? On Jan 13, 2011, at 11:33 AM, Kubila wrote: Hi ALPS users I was wondering can one use looper to simulate quantum XY model with an uniform magnetic field in the x-direction. Thanks.
Hi all It looks like that one can simulate this model with ferromagnetic coupling (the message returned saying that the model has a negative sign if one uses antiferromagnetic coupling). I would like to study magnetization density as a function of external field using loop (since dirloop_sse says that the dirloop_sse for simulating the model is not implemented). Somehow non of the observables look reasonable.... So which observable should I look into in order to study the external field dependence of magnetization density. Thanks. --- On Thu, 1/13/11, Kubila <kubila@yahoo.com> wrote: From: Kubila <kubila@yahoo.com> Subject: Re: [ALPS-users] quantum XY model with an uniform magnetic field in the x-direction To: comp-phys-alps-users@lists.phys.ethz.ch Date: Thursday, January 13, 2011, 5:26 AM Hi Prof. Troyer With antiferromagnetic couplings. --- On Thu, 1/13/11, Matthias Troyer <troyer@phys.ethz.ch> wrote: From: Matthias Troyer <troyer@phys.ethz.ch> Subject: Re: [ALPS-users] quantum XY model with an uniform magnetic field in the x-direction To: comp-phys-alps-users@lists.phys.ethz.ch Date: Thursday, January 13, 2011, 2:44 AM With ferromagnetic or antiferromagnetic couplings? On Jan 13, 2011, at 11:33 AM, Kubila wrote: Hi ALPS users I was wondering can one use looper to simulate quantum XY model with an uniform magnetic field in the x-direction. Thanks.
Dear Kublia, By default, the looper does not calculate quantities related to the transverse magnetization. But, in your case it is straightforward to measure the Zeeman energy just by counting the number of site operators. And then you can extract the transverse magnetization easily. Which version of looper are you using? The one in the ALPS Applications 1.3.x or the one shipped together with ALPS 2.0? Best, Synge On 2011/02/09, at 6:18, Kubila wrote:
Hi all
It looks like that one can simulate this model with ferromagnetic coupling (the message returned saying that the model has a negative sign if one uses antiferromagnetic coupling). I would like to study magnetization density as a function of external field using loop (since dirloop_sse says that the dirloop_sse for simulating the model is not implemented). Somehow non of the observables look reasonable.... So which observable should I look into in order to study the external field dependence of magnetization density. Thanks.
--- On Thu, 1/13/11, Kubila <kubila@yahoo.com> wrote:
From: Kubila <kubila@yahoo.com> Subject: Re: [ALPS-users] quantum XY model with an uniform magnetic field in the x-direction To: comp-phys-alps-users@lists.phys.ethz.ch Date: Thursday, January 13, 2011, 5:26 AM
Hi Prof. Troyer
With antiferromagnetic couplings.
--- On Thu, 1/13/11, Matthias Troyer <troyer@phys.ethz.ch> wrote:
From: Matthias Troyer <troyer@phys.ethz.ch> Subject: Re: [ALPS-users] quantum XY model with an uniform magnetic field in the x-direction To: comp-phys-alps-users@lists.phys.ethz.ch Date: Thursday, January 13, 2011, 2:44 AM
With ferromagnetic or antiferromagnetic couplings?
On Jan 13, 2011, at 11:33 AM, Kubila wrote:
Hi ALPS users
I was wondering can one use looper to simulate quantum XY model with an uniform magnetic field in the x-direction. Thanks.
Dear Synge Thank you very much for your email. I am using ALPS 2.0. It will be great if you can briefly tell me how to modify the code in order to calculate the magnetization density for my model. Also will it be possible to measure the correlation of the first component of magnetization for this model? Many appreciations! Thanks, Kubila --- On Tue, 2/8/11, Kubila <kubila@yahoo.com> wrote: From: Kubila <kubila@yahoo.com> Subject: Re: [ALPS-users] quantum XY model with an uniform magnetic field in the x-direction To: comp-phys-alps-users@lists.phys.ethz.ch Date: Tuesday, February 8, 2011, 1:18 PM Hi all It looks like that one can simulate this model with ferromagnetic coupling (the message returned saying that the model has a negative sign if one uses antiferromagnetic coupling). I would like to study magnetization density as a function of external field using loop (since dirloop_sse says that the dirloop_sse for simulating the model is not implemented). Somehow non of the observables look reasonable.... So which observable should I look into in order to study the external field dependence of magnetization density. Thanks. --- On Thu, 1/13/11, Kubila <kubila@yahoo.com> wrote: From: Kubila <kubila@yahoo.com> Subject: Re: [ALPS-users] quantum XY model with an uniform magnetic field in the x-direction To: comp-phys-alps-users@lists.phys.ethz.ch Date: Thursday, January 13, 2011, 5:26 AM Hi Prof. Troyer With antiferromagnetic couplings. --- On Thu, 1/13/11, Matthias Troyer <troyer@phys.ethz.ch> wrote: From: Matthias Troyer <troyer@phys.ethz.ch> Subject: Re: [ALPS-users] quantum XY model with an uniform magnetic field in the x-direction To: comp-phys-alps-users@lists.phys.ethz.ch Date: Thursday, January 13, 2011, 2:44 AM With ferromagnetic or antiferromagnetic couplings? On Jan 13, 2011, at 11:33 AM, Kubila wrote: Hi ALPS users I was wondering can one use looper to simulate quantum XY model with an uniform magnetic field in the x-direction. Thanks.
On 2011/02/10, at 0:22, Kubila wrote:
Thank you very much for your email. I am using ALPS 2.0. It will be great if you can briefly tell me how to modify the code in order to calculate the magnetization density for my model. Also will it be possible to measure the correlation of the first component of magnetization for this model? Many appreciations!
Please find attached patch to applications/qmc/looper/path_integral.C, by which you can measure the average number of site operators. Since this quantity is related to the total site-term energy, i.e. Zeeman term by the transverse field, by - Gamma * <Sum(S_i^x)> = - T * <Number of Site Operators> + C with C = Gamma/2 in the present specific case, the transverse magnetization per site is given by <S_i^x> = T * <Number of Site Operators> / N / Gamma - 1/2 where T is the temperature, N the number of sites. Best, Synge Index: applications/qmc/looper/path_integral.C =================================================================== --- applications/qmc/looper/path_integral.C (revision 5386) +++ applications/qmc/looper/path_integral.C (working copy) @@ -150,6 +150,7 @@ } looper::energy_estimator::init_observables(obs, model.is_signed()); estimator.init_observables(obs, model.is_signed()); + obs << alps::RealObservable("Number of Site Operators"); } void loop_worker::run(alps::ObservableSet& obs) { @@ -374,6 +375,11 @@ // normal measurement estimator.normal_measurement(obs, lattice, beta, sign, spins, operators, spins_c); + + // counting number of site operators + int num_site_op = 0; + BOOST_FOREACH(local_operator_t& op, operators) if (op.is_site()) ++num_site_op; + obs["Number of Site Operators"] << (double)num_site_op; } typedef looper::evaluator<loop_config::measurement_set> loop_evaluator;
participants (3)
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Kubila
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Matthias Troyer
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Synge Todo