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BEGIN:VEVENT
DTSTAMP:20261019T140306Z
LAST-MODIFIED:20150928T203707Z
DTSTART:20151005T170000Z
DTEND:20151005T180000Z
UID:event1497@bu.edu
URL:http://physics.bu.edu/internal/events/show/1497
SUMMARY:Nucleation in Supercooled Liquids
DESCRIPTION:Featuring Rashi Verma\n\nPart of the Preliminary Oral Exam.\n\n
	Examining Committee:  William Klein\, Tom Keyes\, Ophelia Tsui\, Kevin Blac
	k\n\nAbstract:\nNucleation is the process by which a metastable phase decay
	s into a stable phase. It is widely observed in nature\, and is responsible
	 for many phenomena like cloud formation and crystal growth. The classical 
	nucleation theory predicts a compact droplet of the stable phase that will 
	initiate the nucleation process. For many systems with long range interacti
	ons\, however\, the droplets are highly ramified and harder to locate due t
	o lack of a well-defined structure. This has significant implications for m
	aterial properties.\n\nI have been studying nucleation in Lennard-Jones liq
	uids\, by performing Molecular Dynamics simulations in a Micro-Canonical en
	semble of Argon particles. The system is quenched from liquid temperatures 
	into a metastable solid phase\, and allowed to evolve under constant energy
	 dynamics. Once the nucleus appears and starts to grow\, the time of nuclea
	tion is identified by a method called Intervention. At certain points of th
	e successfully nucleated trajectory\, close to the top of the saddle point 
	free energy barrier\, several copies of the configuration are made with sli
	ghtly perturbed velocities. These copies are allowed to evolve independentl
	y with the same constant energy dynamics\, and the number of successfully n
	ucleated copies are counted to get the success ratio. Ideally\, one would e
	xpect a monotonic rise in the the success ratio as we approach the energy b
	arrier and cross over it. However\, I observed a non-monotonic behavior for
	 deep quenches closer to the spinodal. This non-monotonicity is not a stati
	stical fluctuation\, since it persists despite increasing the number of cop
	ies. The question we are pursuing is: Could this be an inherent property of
	 spinodal nucleation\, and provide us with new insights into the free energ
	y landscape? In addition I am investigating the symmetry of the critical nu
	cleus by pinpointing its exact location and time of appearance and employin
	g spherical harmonics to identify the spatial arrangement of molecules.\n\n
	 \n\n![Rashi Verma](/resources/event-image/1497/949cc73_small)
LOCATION:SCI 328\, 590 Commonwealth Avenue\, 02215
STATUS:CONFIRMED
CLASS:PUBLIC
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