#
2009 APS March Meeting

## Volume 54, Number 1

##
Monday–Friday, March 16–20, 2009;
Pittsburgh, Pennsylvania

### Session L8: Jamming at Nonzero Temperature and Stress

2:30 PM–5:30 PM,
Tuesday, March 17, 2009

Room: 414/415

Sponsoring
Units:
DCMP GSNP

Chair: Vincenzo Vitelli, University of Pennsylvania

Abstract ID: BAPS.2009.MAR.L8.1

### Abstract: L8.00001 : Simple scaling of the glass transition temperature with pressure*

2:30 PM–3:06 PM

Preview Abstract
Abstract

####
Author:

Ning Xu

(University of Pennsylvania and University of Chicago)

Zero-temperature packings of frictionless spheres have been used
as a starting point for understanding granular materials, foams,
colloids and even glass-forming liquids. Such packings exhibit a
jamming transition, known as Point J, with increasing packing
fraction. This symposium presents recent work that explores the
implications of Point J for systems at nonzero temperature, shear
stress, or friction. In this talk, I present results that push
beyond zero temperature to explore the connection between Point J
and the glass transition. We performed molecular dynamics
simulations of several three-dimensional models of glass-forming
liquids, and measured the relaxation time from the intermediate
scattering function along several trajectories to the glass
transition, such as lowering temperature at fixed packing
fraction, or raising pressure at fixed temperature. Along each
trajectory, we extrapolated the relaxation time using the form
$\tau={\rm exp}(A/(T-T_0)^{\alpha})$ or $\tau={\rm
exp}(A/(p^r-p^r_0)^{\alpha})$, depending on whether temperature or
pressure was varied, where $p^r$ is the contribution to the
pressure from repulsive forces, only. Here, $A$, $\alpha$,
$T_0$ and $p^r_0$ are fit parameters. We find that $T_0$ is
linear in the repulsive contribution to the pressure, $p^r$:
$T_0=vp^r$. The fit parameter $v$ is approximately
$0.035v_0=(0.37\sigma)^3$, independent of potential, where $v_0$
is the average volume per particle and $\sigma$ is the diameter
of the particle. This linear scaling of $T_0$ with $p^r$ holds
very well at low $p^r$, which corresponds to the vicinity of
Point J in purely repulsive systems where jamming transition at
T=0 exists. This suggests that Point J marks the onset of a
nonzero value of the glass transition temperature, $T_0$.
Experimental data for glycerol (K. Z. Win and N. Menon, Phys.
Rev. E 73, 040501 (2006)) also show that $T_0$ is linear in
pressure, with a prefactor of 0.04$\times$ the molecular volume.

*Supported by DE-FG02-05ER46199 and DE-FG02-03ER46088.

To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2009.MAR.L8.1