Levich Institute Seminar Announcement, 02/02/2010
Tuesday, 02/02/2010
2:00 PM
Steinman Hall, Room #312
(Chemical Engineering Conference Room)

Dr. Ashwin Selvarajan Sampangiraj
Yale University
Department of Chemical Engineering

"Fragility Transition and the Density Landscape"


ABSTRACT

When a fluid is not allowed to crystallize upon cooling or compression, its dynamics greatly slows down. When the relaxation times of the fluid is of the order of 100s, one identifies such a fluid as a glass and this transition is known as the glass transition. Glass forming liquids are broadly classified by their so called fragility. Fragility is a classification based on the behavior of the viscosity of the fluid with respect to temperature, when it is Arrhenius the liquid is called strong and when it is non-Arrhenius it is said to be fragile. The origin of this varying fragilities for fluids has been hotly debated for over three decades, without much consensus. We present here an model fluid which shows a fragility cross over from fragile to strong at high volume fractions. We calculate the partition function of the model fluid and present a novel analytico-geometric scheme to relate the fluid to its underlying density landscape and also calculate its configurational entropy exactly. This provides much insight into the mechanism of fragility cross over.