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TZID:Europe/Paris
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BEGIN:VEVENT
UID:0-684@lptms.universite-paris-saclay.fr
DTSTART:20191001T110000Z
DTEND:20191001T120000Z
DTSTAMP:20190922T221850Z
URL:http://www.lptms.universite-paris-saclay.fr/seminars/seminaire-du-lptm
s-werner-krauth-lpens/
SUMMARY:Séminaire du LPTMS: Werner Krauth (LPENS) - Salle des séminaires
du FAST et du LPTMS\, bâtiment Pascal n°530 - 1 Oct 19 11:00
DESCRIPTION:Fast irreversible Markov chains in statistical physics\nWerner
Krauth (LPENS)\nThe Monte Carlo method is an outstanding computational too
l in science. Since its origins\, it has relied on the detailed-balance co
ndition (that is\, the absence of flows in equilibrium) to map general com
putational problems onto equilibrium-statistical-physics systems.\n\nIrrev
ersible Markov chains violate the detailed-balance condition. They realize
the equilibrium Boltzmann distribution as a steady state with non-vanishi
ng flows. For one-dimensional particle models we have proven rigorously th
at local algorithms reach equilibrium on much faster time scales than the
reversible algorithms that satisfy detailed balance. The event-chain Monte
Carlo algorithm (ECMC) generalizes these irreversible Markov chains to hi
gher dimensions. It relies on a factorized Metropolis filter which is base
d on a consensus rule rather than on an energy criterion.\n\nAs applicatio
ns I will discuss the solution of the famous two-dimensional melting prob
lem for hard disks and related systems\, where we showed\, using ECMC\,
that hard disks melt neither following the Kosterlitz-Thouless-Halperin-Ne
lson-Young prescription nor the alternative first-order liquid-solid scena
rio. I will also present the use of ECMC for the general classical all-ato
m N-body problem. Here\, the Boltzmann distribution exp(-beta E) is sample
d (without any discretization or truncation error) but the potential energ
y E remains unknown. This is of great interest in the Coulomb problem\, wh
ere E or its derivatives\, the forces\, are hard to compute. Our recent Je
LLyFysh open-source Python application implements ECMC for models from har
d spheres to three-dimensional water systems. I will finish by discussing
its features\, that closely mirror the mathematical formulation of ECMC\,
and by presenting its future challenges.
CATEGORIES:seminars
LOCATION:Salle des séminaires du FAST et du LPTMS\, bâtiment Pascal n°53
0\, rue André Riviere\, Orsay\, 91405\, France
X-APPLE-STRUCTURED-LOCATION;VALUE=URI;X-ADDRESS=rue André Riviere\, Orsay\
, 91405\, France;X-APPLE-RADIUS=100;X-TITLE=Salle des séminaires du FAST
et du LPTMS\, bâtiment Pascal n°530:geo:0,0
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