Sat, 26 Jul 2008 06:17:41 BST CiteULike: dchen's Stillinger http://www.citeulike.org/user/dchen/author/Stillinger CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/user/dchen/article/2883376 <i>Physical Review E (Statistical, Nonlinear, and Soft Matter Physics), Vol. 75, No. 5. (2007)</i><br /><br />Continuing on recent computational and experimental work on jammed packings of hard ellipsoids [Donev et al., Science 303, 990 (2004)] we consider jamming in packings of smooth strictly convex nonspherical hard particles. We explain why an isocounting conjecture, which states that for large disordered jammed packings the average contact number per particle is twice the number of degrees of freedom per particle (=2df), does not apply to nonspherical particles. We develop first- and second-order conditions for jamming and demonstrate that packings of nonspherical particles can be jammed even though they are underconstrained (hypoconstrained, <2df). We apply an algorithm using these conditions to computer-generated hypoconstrained ellipsoid and ellipse packings and demonstrate that our algorithm does produce jammed packings, even close to the sphere point. We also consider packings that are nearly jammed and draw connections to packings of deformable (but stiff) particles. Finally, we consider the jamming conditions for nearly spherical particles and explain quantitatively the behavior we observe in the vicinity of the sphere point. Underconstrained jammed packings of nonspherical hard particles: Ellipses and ellipsoids Aleksandar Donev Robert Connelly Frank Stillinger Salvatore Torquato doi:10.1103/PhysRevE.75.051304 Physical Review E (Statistical, Nonlinear, and Soft Matter Physics), Vol. 75, No. 5. (2007) 2008-06-11T16:29:28-00:00 2007 Physical Review E (Statistical, Nonlinear, and Soft Matter Physics) 75 5 APS 2008 ellipsoid packing pre stillinger theory http://www.citeulike.org/user/dchen/article/1309740 <i>Science, Vol. 267, No. 5206. (31 March 1995), pp. 1935-1939.</i><br /><br />Various static and dynamic phenomena displayed by glass-forming liquids, particularly those near the so-called "fragile" limit, emerge as manifestations of the multidimensional complex topography of the collective potential energy function. These include non-Arrhenius viscosity and relaxation times, bifurcation between the [agr]- and [beta]-relaxation processes, and a breakdown of the Stokes-Einstein relation for self-diffusion. This multidimensional viewpoint also produces an extension of the venerable Lindemann melting criterion and provides a critical evaluation of the popular "ideal glass state" concept. 10.1126/science.267.5206.1935 A Topographic View of Supercooled Liquids and Glass Formation Frank Stillinger doi:10.1126/science.267.5206.1935 Science, Vol. 267, No. 5206. (31 March 1995), pp. 1935-1939. 2007-05-19T22:04:07-00:00 1995 Science 267 5206 1935 1939 classic glass science stillinger theory http://www.citeulike.org/user/dchen/article/2713802 <i>Science, Vol. 303, No. 5660. (13 February 2004), pp. 990-993.</i><br /><br />Packing problems, such as how densely objects can fill a volume, are among the most ancient and persistent problems in mathematics and science. For equal spheres, it has only recently been proved that the face-centered cubic lattice has the highest possible packing fraction [IMG]f1.gif" BORDER="0">. It is also well known that certain random (amorphous) jammed packings have varphi approx 0.64. Here, we show experimentally and with a new simulation algorithm that ellipsoids can randomly pack more densely--up to varphi= 0.68 to 0.71for spheroids with an aspect ratio close to that of M&M's Candies--and even approach varphi approx 0.74 for ellipsoids with other aspect ratios. We suggest that the higher density is directly related to the higher number of degrees of freedom per particle and thus the larger number of particle contacts required to mechanically stabilize the packing. We measured the number of contacts per particle Z approx 10 for our spheroids, as compared to Z approx 6 for spheres. Our results have implications for a broad range of scientific disciplines, including the properties of granular media and ceramics, glass formation, and discrete geometry. 10.1126/science.1093010 Improving the Density of Jammed Disordered Packings Using Ellipsoids Aleksandar Donev Ibrahim Cisse David Sachs Evan Variano Frank Stillinger Robert Connelly Salvatore Torquato PM Chaikin doi:10.1126/science.1093010 Science, Vol. 303, No. 5660. (13 February 2004), pp. 990-993. 2008-04-24T18:23:40-00:00 2004 Science 303 5660 990 993 ellipsoid jamming packing science stillinger http://www.citeulike.org/user/dchen/article/2467580 <i>Science (1998)</i> Signatures of distinct dynamical regimes in the energy landscape of a glass-forming liquid Srikanth Sastry Pablo Debenedetti Frank Stillinger Science (1998) 2008-03-04T20:18:35-00:00 1998 Science landscape simulation stillinger http://www.citeulike.org/user/dchen/article/1201309 <i>Nature, Vol. 410, No. 6825. (March 2001), pp. 259-267.</i> Supercooled liquids and the glass transition Pablo Debenedetti Frank Stillinger doi:10.1038/35065704 Nature, Vol. 410, No. 6825. (March 2001), pp. 259-267. 2007-04-01T02:48:59-00:00 2001 Nature 410 6825 259 267 glass review stillinger supercooled