BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//talks.cam.ac.uk//v3//EN
BEGIN:VTIMEZONE
TZID:Europe/London
BEGIN:DAYLIGHT
TZOFFSETFROM:+0000
TZOFFSETTO:+0100
TZNAME:BST
DTSTART:19700329T010000
RRULE:FREQ=YEARLY;BYMONTH=3;BYDAY=-1SU
END:DAYLIGHT
BEGIN:STANDARD
TZOFFSETFROM:+0100
TZOFFSETTO:+0000
TZNAME:GMT
DTSTART:19701025T020000
RRULE:FREQ=YEARLY;BYMONTH=10;BYDAY=-1SU
END:STANDARD
END:VTIMEZONE
BEGIN:VEVENT
CATEGORIES:Isaac Newton Institute Seminar Series
SUMMARY:Fast Reactive Brownian Dynamics - Aleksandar Donev
(New York University)
DTSTART;TZID=Europe/London:20160621T090000
DTEND;TZID=Europe/London:20160621T094500
UID:TALK66529AThttp://talks.cam.ac.uk
URL:http://talks.cam.ac.uk/talk/index/66529
DESCRIPTION:I will describe a particle-based algorithm for rea
ction-diffusion problems that combines Brownian d
ynamics with a Markov reaction process. The micros
copic model simulated by our Split Reactive Brown
ian Dynamics (SRBD) algorithm is based on the Doi
or volume-reactivity model. This model applies on
ly to reactions with at most two reactants\, whic
h is physically realistic. Let us consider the si
mple reaction A+B->product. In the Doi model\, par
ticles are independent spherical Brownian walkers
(this can be relaxed to account for hydrodynamic
interactions)\, and while an A and a B particle o
verlap\, there is a Poisson process with a given
microscopic reaction rate for the two particles to
react and give a product. Our goal is to simulat
e this complex Markov process in dense systems of
many particles\, in the presence of multiple reac
tion channels.

Our algorithm is inspired
by the Isotropic Direct Simulation Monte Carlo (
I-DSMC) method and the next subvolume method. Stra
ng splitting is used to separate diffusion and re
action\; this is the only approximation made in ou
r method. In order to process reactions without a
pproximations\, with the particles frozen in plac
e\, we use an event-driven algorithm. We divide th
e system into a grid of cells such that only part
icles in neighboring cells can react. Each cell s
chedules the next potential reaction to happen inv
olving a particle in that cell and a particle in
one of the neighboring cells\, and an event queue
is used to select the next cell in which a reacti
on may happen.

Note that\, while a
grid of cells is used to make the algorithm effici
ent\, the results obtained by the SRBD method are
grid-independent and thus free of grid artifacts
\, such as loss of Galilean invariance and sensiti
vity of the results to the grid spacing. I will c
ompare our SRBD method with grid-based methods\, s
uch as (C)RDME and a variant of RDME that we call
Split Brownian Dynamics with Reaction Master Equ
ation (S-BD-RME)\, on a problem involving the spon
taneous f
LOCATION:Seminar Room 1\, Newton Institute
CONTACT:INI IT
END:VEVENT
END:VCALENDAR