http://www.lps.ens.fr/~krauth/index.php?title=Special:Recentchanges&days=30&hideminor=1&hidepatrolled=1&hidemyself=1&feed=atomWerner KRAUTH - Recent changes [en]2016-06-28T09:19:28ZTrack the most recent changes to the wiki on this page.MediaWiki 1.6.12http://www.lps.ens.fr/~krauth/index.php/Kapfer_Krauth_2016Kapfer Krauth 20162016-06-28T09:09:59Z<p>/* Illustration */ </p>
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<td colspan='2' width='50%' align='center' style="background-color: white;">Revision as of 09:09, 28 June 2016</td>
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<tr><td> </td><td style="background: #eee; font-size: smaller;">=Illustration=</td><td> </td><td style="background: #eee; font-size: smaller;">=Illustration=</td></tr>
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<tr><td>-</td><td style="background: #ffa; font-size: smaller;">The cell-veto algorithm is an application of the event-chain paradigm that was developed in 2009, with [[Bernard_Krauth_Wilson_2009|E. P. Bernard and D. B. Wilson]], and much extended together with [[Michel_Kapfer_Krauth_2013|M. Michel and S. C. Kapfer]], where we introduced the factorized Metropolis algorithm. In this algorithm, unlike in 99.9% of all simulation algorithms (Monte Carlo or Molecular dynamics), one does not compute the system energy in order to decide on a change of the physical system, but rather looks at all the interactions separately. So, if a particle '''a''' (the active particle), it has to ask all its partners '''t_1''', '''t_2''', .... (the target particles). If there is only a single veto, the move is <span style="color: red; font-weight: bold;">not undertaken</span>. <span style="color: red; font-weight: bold;">What may sound weird </span>is in <span style="color: red; font-weight: bold;">fact</span></td><td>+</td><td style="background: #cfc; font-size: smaller;"><span style="color: red; font-weight: bold;">[[Image:Kapfer Krauth Cell Schema.png|left|600px|border|Here are pictures of three bosons on an permutation cycle.]]</span>The cell-veto algorithm is an application of the event-chain paradigm that was developed in 2009, with [[Bernard_Krauth_Wilson_2009|E. P. Bernard and D. B. Wilson]], and much extended together with [[Michel_Kapfer_Krauth_2013|M. Michel and S. C. Kapfer]], where we introduced the factorized Metropolis algorithm. In this algorithm, unlike in 99.9% of all simulation algorithms (Monte Carlo or Molecular dynamics), one does not compute the system energy in order to decide on a change of the physical system, but rather looks at all the interactions separately. So, if a particle '''a''' (the active particle) <span style="color: red; font-weight: bold;">wants to move</span>, it has to ask all its partners '''t_1''', '''t_2''', .... (the target particles). If there is only a single veto, the move is <span style="color: red; font-weight: bold;">rejected</span>. <span style="color: red; font-weight: bold;">In the cell-veto algorithm (see the right side of the figure), the identification of the rejecting particle </span>is <span style="color: red; font-weight: bold;">preceeded by that of a veto cell. The advantage of this is that cell vetos can be identified immediately (</span>in <span style="color: red; font-weight: bold;">a constant number of operations, that is, in O(1)), and then instantly confirmed or infirmed on the particle level.</span></td></tr>
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Wernerhttp://www.lps.ens.fr/~krauth/index.php/Special:Log/uploadSpecial:Log/upload2016-06-28T09:00:31Z<p>uploaded "[[Image:Kapfer Krauth Cell Schema.png]]"</p>
Wernerhttp://www.lps.ens.fr/~krauth/index.php/Kapfer_Krauth_2016Kapfer Krauth 20162016-06-28T08:54:09Z<p></p>
<p><b>New page</b></p><div>'''S. C. Kapfer, W. Krauth''' '''''Cell-veto Monte Carlo algorithm for long-range systems''''' '''arXiv:1606.06780 (2016)'''<br />
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=Paper=<br />
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'''Abstract''' <br />
We present a rigorous efficient event-chain Monte Carlo algorithm for long-range interacting particle systems. Using a cell-veto scheme within the factorized Metropolis algorithm, we compute each single-particle move with a fixed number of operations. For slowly decaying potentials such as Coulomb interactions, screening line charges allow us to take into account periodic boundary conditions. We discuss the performance of the cell-veto Monte Carlo algorithm for general inverse-power-law potentials, and illustrate how it provides a new outlook on one of the prominent bottlenecks in large-scale atomistic Monte Carlo simulations. <br />
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[http://arxiv.org/pdf/1606.06780 Electronic version (from arXiv)]<br />
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=Illustration=<br />
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The cell-veto algorithm is an application of the event-chain paradigm that was developed in 2009, with [[Bernard_Krauth_Wilson_2009|E. P. Bernard and D. B. Wilson]], and much extended together with [[Michel_Kapfer_Krauth_2013|M. Michel and S. C. Kapfer]], where we introduced the factorized Metropolis algorithm. In this algorithm, unlike in 99.9% of all simulation algorithms (Monte Carlo or Molecular dynamics), one does not compute the system energy in order to decide on a change of the physical system, but rather looks at all the interactions separately. So, if a particle '''a''' (the active particle), it has to ask all its partners '''t_1''', '''t_2''', .... (the target particles). If there is only a single veto, the move is not undertaken. What may sound weird is in fact</div>Wernerhttp://www.lps.ens.fr/~krauth/index.php/Comparin_Krauth_2016aComparin Krauth 2016a2016-06-05T00:11:48Z<p></p>
<p><b>New page</b></p><div>'''T. Comparin, W. Krauth''' '''''Momentum distribution in the unitary Bose gas from first principles''''' '''arXiv:1604.08870 (2016)'''<br />
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=Paper=<br />
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'''Abstract''' <br />
Ultracold atomic gases have over the last decades boosted the understanding of quantum physics in the whole range from weak interactions to the infinite-interaction unitary limit. The latter has lead to a revival of the celebrated Efimov effect, that had only been hypothesized in nuclear matter. Here we present first-principles quantum Monte Carlo results for a realistic bosonic N-particle model with infinite, unitary, interactions. We compute the critical temperature for Bose-Einstein condensation and determine the full momentum distribution, including its universal asymptotic behavior. We compare this crucial observable to recent experimental data. The weak dependence of physical observables on the sole parameter of the model, the three-body cutoff, supports its universality. We argue that the thermodynamic instability from the atomic gas towards an Efimov liquid remains hidden by the experimental dynamical instability caused by three-body losses. <br />
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[http://arxiv.org/pdf/1604.08870 Electronic version (from arXiv)]</div>Wernerhttp://www.lps.ens.fr/~krauth/index.php/Publications_WKPublications WK2016-06-05T00:07:21Z<p>/* Recent publications and preprints */ </p>
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<td colspan='2' width='50%' align='center' style="background-color: white;">Revision as of 00:07, 5 June 2016</td>
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<tr><td> </td><td style="background: #eee; font-size: smaller;">=Recent publications and preprints=</td><td> </td><td style="background: #eee; font-size: smaller;">=Recent publications and preprints=</td></tr>
<tr><td colspan="2"> </td><td>+</td><td style="background: #cfc; font-size: smaller;">[[Comparin_Krauth_2016a|T. Comparin, W. Krauth</td></tr>
<tr><td colspan="2"> </td><td>+</td><td style="background: #cfc; font-size: smaller;">''Momentum distribution in the unitary Bose gas from first principles''</td></tr>
<tr><td colspan="2"> </td><td>+</td><td style="background: #cfc; font-size: smaller;">arXiv:1604.08870 (2016)]]</td></tr>
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<tr><td> </td><td style="background: #eee; font-size: smaller;">[[Nishikawa_Michel_Krauth_Hukushima_2015|Y. Nishikawa, M. Michel, W. Krauth, K. Hukushima ''Event-chain algorithm for the Heisenberg model: Evidence for z \sim 1 dynamic scaling'' Physical Review E 92, 063306 (2015)]]</td><td> </td><td style="background: #eee; font-size: smaller;">[[Nishikawa_Michel_Krauth_Hukushima_2015|Y. Nishikawa, M. Michel, W. Krauth, K. Hukushima ''Event-chain algorithm for the Heisenberg model: Evidence for z \sim 1 dynamic scaling'' Physical Review E 92, 063306 (2015)]]</td></tr>
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Werner