Sat, 26 Jul 2008 08:33:34 BST CiteULike: dchen cooperative http://www.citeulike.org/user/dchen/tag/cooperative CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/user/dchen/article/2749189 <i>Physical Review B (Condensed Matter and Materials Physics), Vol. 77, No. 13. (2008)</i><br /><br />Homogeneous melting in the superheating regime is investigated by using molecular dynamics simulation of a Lennard-Jones model system. We show that the commonly observed catastrophic melting at the superheating limit is caused by fast heating rate. By keeping the system isothermally at temperatures below the superheating limit, we observe intense self-diffusion motions as the precursor of melting. The highly correlated atomic motions are related to the self-diffusion loops or rings. Two types of loops are observed, closed loop and open loop, where the latter is directly related to the homogeneous nucleation of the liquid phase. Homogeneous melting occurs when the number density of diffusion loops reaches a critical value. Our results suggest that homogeneous melting in the superheating regime is a first-order thermodynamic phase transition triggered by the self-diffusion loops when the kinetic constraint imposed by heating rate is lessened. Ring-diffusion mediated homogeneous melting in the superheating regime Xian Bai Mo Li doi:10.1103/PhysRevB.77.134109 Physical Review B (Condensed Matter and Materials Physics), Vol. 77, No. 13. (2008) 2008-05-03T15:47:24-00:00 2008 Physical Review B (Condensed Matter and Materials Physics) 77 13 APS 2008 cooperative crystal dynamics focus simulation transition http://www.citeulike.org/user/dchen/article/822249 <i>Physical Review Letters, Vol. 85, No. 8. (2000), 1774.</i><br /><br />We study the dynamics of rigid spheres embedded in viscoelastic media and address two questions of importance to microrheology. First; we calculate the complete response to an external force of a single bead in a homogeneous elastic network viscously coupled to an incompressible fluid. From this response function we find the frequency range where the standard assumptions of microrheology are valid. Second; we study fluctuations when embedded spheres perturb the media around them and show that mutual fluctuations of two separated spheres provide a more accurate determination of the complex shear modulus than do the fluctuations of a single sphere. One- and Two-Particle Microrheology Alex Levine TC Lubensky doi:10.1103/PhysRevLett.85.1774 Physical Review Letters, Vol. 85, No. 8. (2000), 1774. 2006-08-30T16:26:55-00:00 2000 Physical Review Letters 85 8 1774 American Physical Society cooperative diffusion microrheology http://www.citeulike.org/user/dchen/article/2730829 <i>Physical Review E, Vol. 61, No. 6. (1 June 2000), 7260.</i> Erratum: Experimental observations of non-Gaussian behavior and stringlike cooperative dynamics in concentrated quasi-two-dimensional colloidal liquids [Phys. Rev. E 60, 5725 (1999)] Andrew Marcus Jeremy Schofield Stuart Rice doi:10.1103/PhysRevE.61.7260 Physical Review E, Vol. 61, No. 6. (1 June 2000), 7260. 2008-04-28T19:10:11-00:00 2000 Physical Review E 61 6 7260 American Physical Society 2d cooperative dynamics structure supercooled http://www.citeulike.org/user/dchen/article/2675305 <i>Physical Review B (Condensed Matter and Materials Physics), Vol. 74, No. 11. (2006)</i><br /><br />Molecular dynamics simulations were employed to study atomic motion within stationary and migrating asymmetric tilt grain boundaries. We employ several measures of the "complexity" of the atomic trajectories, including the van Hove correlation function, the non-Gaussian parameter, and dynamic entropy. There are two key types of dynamical events within the grain boundaries (i) a stringlike cooperative motions parallel to the tilt axis and occurring on a characteristic time scale of 25  ps and (ii) atomic motion across the grain boundary plane occurring on a characteristic time scale of 150  ps. The characteristic times associated with each type of event decreases with increasing driving force for boundary migration. We present evidence as to how the driving force biases these types of events, leading to boundary migration. While the stringlike atomic motion is an intrinsic feature of grain boundary dynamics and is important for grain boundary migration, it is the second type of event that controls grain boundary migration rates. Characterization of atomic motion governing grain boundary migration Hao Zhang David Srolovitz Jack Douglas James Warren doi:10.1103/PhysRevB.74.115404 Physical Review B (Condensed Matter and Materials Physics), Vol. 74, No. 11. (2006) 2008-04-15T20:22:51-00:00 2006 Physical Review B (Condensed Matter and Materials Physics) 74 11 APS cluster cooperative grain http://www.citeulike.org/user/dchen/article/2613959 <i></i> The shapes of cooperatively rearranging regions in glass-forming liquids 2008-03-30T21:25:02-00:00 cooperative glass nature