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CATEGORIES:DAMTP Statistical Physics and Soft Matter Seminar
SUMMARY:Proper Statistical Sampling in Isothermal-Isobaric
Discrete-Time Molecular Dynamics - Prof. Oded Far
ago (Ben Gurion and Cambridge Chemistry)
DTSTART;TZID=Europe/London:20190122T130000
DTEND;TZID=Europe/London:20190122T140000
UID:TALK116263AThttp://talks.cam.ac.uk
URL:http://talks.cam.ac.uk/talk/index/116263
DESCRIPTION:Abstract: Molecular Dynamics simulations always in
volve a discretization of time\, but the discrete-
time behavior is increasingly different from that
of the continuous-time physical equations as the t
ime step is increased. This fact creates a dilemma
for any simulation of a dynamical system: Use a s
mall time step\, resulting in dynamics that resemb
le continuous-time behavior at the expense of effi
ciency\; or use a large time step that makes the s
imulation finish sooner at the expense of meaningf
ul evolution. It is\, therefore\, essential to und
erstand the features of different algorithms\, suc
h that optimal properties can be chosen for a give
n set of problems and objectives.\n\nOur aim is to
investigate and improve Molecular Dynamics simula
tion techniques for systems in thermal equilibrium
. I will present a simple derivation of a stochast
ic Stormer-Verlet algorithm for the evolution of L
angevin equations. The method\, which is as simple
as conventional Verlet schemes\, has been numeric
ally tested on both low-dimensional nonlinear syst
ems as well as more complex molecular ensembles wi
th many degrees of freedom. In light of the fundam
ental artifacts introduced by discrete time to dyn
amical simulations\, I will provide a simple intui
tive picture of the unique benefits of our algorit
hm that\, unlike other algorithms\, preserves prop
er configurational sampling (diffusion and Boltzma
nn distribution) in discrete time. I will also int
roduce a companion algorithm for controlling press
ure in molecular ensembles\, i.e.\, a barostat for
NPT simulations.
LOCATION:MR11\, CMS
CONTACT:Professor Mike Cates
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