Harrowell, Peter - University of Sydney

研究领域

statistical mechanics nucleation crystal growth rheology of ordered materials transitions in nonequilibrium systems computer simulation methods liquid crystals glass transitions theory of highly cooperative dynamics the physics of biological processes history of science Glass Transition: We are carrying out detailed analysis of the nature of slow relaxation in some simple models of glass forming liquids using computer simulations and theoretical treatments. In studies of a facilitated kinetic Ising model [Harrowell, Phys.Rev.E, 48, 4359 (1993)] we concluded that the glassy dynamics was the result of an increasing inhomogeneity in the spatial distribution of relaxation kinetics. This insight has proved a valuable approach to the analysis of structural relaxation in simple liquids [Hurley and Harrowell, Phys.Rev.E, 52, 1694 (1995), J.Chem.Phys., to be published (1996)]. It also provides a valuable general framework with which to relate the range of glass behaviour [Perera and Harrowell, Phys.Rev.E, 54, 1652 (1996)]. We are currently undertaking a detailed study of nature of relaxation and structural fluctuations in supercooled biinary liquid mixtures in 2D using molecular dynamic simulations and theoretical descriptions of the collective processes. Shear Induced Transitions in Colloidal Suspensions: Extensive nonequilibrium simulations of dilute suspensions of charged colloidal particles have been undertaken with the aim of establishing the correct physical picture of the order/disorder transitions observed experimentally under the influence of shear. We have reproduced the shear induced disordering transition observed in colloidal crystals [Butler and Harrowell, J.Chem.Phys. 103, 4653 (1995)] and established that long wavelength fluctuations play a central role in the transition, unlike its equilibrium analogue. We have also demonstrated that the frequently reported observation of shear induced ordering in simulated liquids CAN arise as an artefact of shearing a liquid through periodic boundary conditions [Butler and Harrowell, J.Chem.Phys. 105, 605 (1996)]. The kinetics of crystallization in a shearing suspension has also been examined [Butler and Harrowell, Phys.Rev.E, 52, 6424 (1996)]. Current work focuses on developing a clearer insight into the coupling of shear flow with structural fluctuations. The Stabilization of Layered Liquid Crystal Phases: We have just completed a Monte Carlo simulation study of the role of flexible end chains on stabilizing Smectic A and Smectic C phases of liquid crystals. We have demonstrated for the first time that both phases can be stabilized from purely entropic effects [Casey and Harrowell, in preparation]. Ongoing work involves the study of phase transitions in small clusters of mesogens. Crystal Growth: Our current work involves looking at two questions. The first is the description of crystallization involving density change under conditions of constant N and V (as is often the case). Under these conditions the supercooling is, itself, varying with time [Wild and Harrowell, in preparation]. The second problem considers the relationship between a crystal surface's ability to organize the adjacent liquid and the kinetics of the growth process. Our current work builds on earlier results [Williams, Moss and Harrowell, J.Chem.Phys. 99, 3998 (1993); Moss and Harrowell, J.Chem.Phys. 100, 7630 (1994)] in which we showed that close packed surfaces with short range interactions were unable to fully break the symmetry of the adjacent liquid and hence the growth of these surfaces was impeded.

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Douglass, I., Hudson, T., Harrowell, P. (2016). Density and glass forming ability in amorphous atomic alloys: The role of the particle softness. Journal of Chemical Physics, 144(14), 1-8. [More Information] Chowdhury, S., Abraham, S., Hudson, T., Harrowell, P. (2016). Long range stress correlations in the inherent structures of liquids at rest. Journal of Chemical Physics, 144(12), 1-6. [More Information] Saw, S., Harrowell, P. (2016). Rigidity in condensed matter and its origin in configurational constraint. Physical Review Letters, 116(13), 1-5. [More Information] Ramsay, M., Harrowell, P. (2016). Shear melting at the crystal-liquid interface: Erosion and the asymmetric suppression of interface fluctuations. Physical Review E (Statistical, Nonlinear, and Soft Matter Physics), 93(4), 1-5. [More Information] Ronceray, P., Harrowell, P. (2016). The free energy of a liquid when viewed as a population of overlapping clusters. Molecular Simulation, 42(13), 1149-1156. [More Information] Ronceray, P., Harrowell, P. (2015). Favoured local structures in liquids and solids: a 3D lattice model. Soft Matter, 11(17), 3322-3331. [More Information] Jennings, C., Ramsay, M., Hudson, T., Harrowell, P. (2015). Packing concave molecules in crystals and amorphous solids: on the connection between shape and local structure. Molecular Physics, 113(17-18), 2755-2769. [More Information] Saw, S., Harrowell, P. (2015). The geometric mean squared displacement and the Stokes-Einstein scaling in a supercooled liquid. Journal of Chemical Physics, 143(24), 244502-1-244502-4. [More Information] Tondl, E., Ramsay, M., Harrowell, P., Widmer-Cooper, A. (2014). Defect-mediated relaxation in the random tiling phase of a binary mixture: Birth, death and mobility of an atomic zipper. Journal of Chemical Physics, 140(10), 1-8. [More Information] Ronceray, P., Harrowell, P. (2014). Multiple Ordering Transitions in a Liquid Stabilized by Low Symmetry Structures. Physical Review Letters, 112(1), 1-5. [More Information] Tang, C., Harrowell, P. (2013). Anomalously slow crystal growth of the glass-forming alloy CuZr. Nature Materials, 12(6), 507-511. [More Information] Douglass, I., Harrowell, P. (2013). Can a stable glass be superheated? Modelling the kinetic stability of coated glassy films. Journal of Chemical Physics, 138(12), 1-6. [More Information] Ronceray, P., Harrowell, P. (2013). Influence of liquid structure on the thermodynamics of freezing. Physical Review E (Statistical, Nonlinear, and Soft Matter Physics), 87(5), 1-10. [More Information] Ronceray, P., Harrowell, P. (2012). Geometry and the entropic cost of locally favoured structures in a liquid. Journal of Chemical Physics, 136(13), 134504-1-134504-4. [More Information] Huang, D., Harrowell, P. (2012). Molecular shape and the energetics of chemisorption: From simple to complex energy landscapes. Physical Review E (Statistical, Nonlinear, and Soft Matter Physics), 86(1), 1-8. [More Information] Ediger, M., Harrowell, P. (2012). Perspective: Supercooled liquids and glasses. Journal of Chemical Physics, 137(8), 080901-1-080901-15. [More Information] Tang, C., Harrowell, P. (2012). Predicting the solid state phase diagram for glass-forming alloys of copper and zirconium. Journal of Physics: Condensed Matter, 24(24), 1-7. [More Information] de Souza, V., Harrowell, P. (2012). Structurally determined directionality identifies the boundary between mobile and immobile domains in a disordered material. Journal of Chemical Physics, 136(5), 1-3. [More Information] Abraham, S., Harrowell, P. (2012). The origin of persistent shear stress in supercooled liquids. Journal of Chemical Physics, 137(1), 1-8. [More Information] Huang, D., Harrowell, P. (2011). Controlling adsorbate diffusion on a high-symmetry surface through molecular shape selection. The Journal of Physical Chemistry Part C, 115(19), 9526-9534. [More Information]