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Professor Peter R Harrowell

Professor of Chemistry and Director of Postgraduate Studies

Contact Details

School of Chemistry, Building F11
The University of Sydney, NSW, 2006
Australia
Email address: peter.harrowell@sydney.edu.au
Telephone: +61 (2)9351-4102
Fax: +61 (2) 9351-3329

Career Profile

B.Sc. (University of Sydney)
Ph.D. (University of Chicago)

Areas of interest

  • 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

Research

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.

Publications (2007 to 2010)

  1. Widmer-Cooper, A and Harrowell, P. Central role of thermal collective strain in the relaxation of structure in a supercooled liquid. Physical Review E, 80 (6), 061501 (6 pages), 2009. DOI: 10.1103/PhysRevE.80.061501

  2. Widmer-Cooper, A; Perry, H; Harrowell, P and Reichman, DR. Localized soft modes and the supercooled liquid’s irreversible passage through its configuration space. The Journal of Chemical Physics, 131 (19), 194508 (12 pages), 2009. DOI: 10.1063/1.3265983

  3. de Souza, VK and Harrowell, P. Unconstrained motions, dynamics heterogeneities, and relaxation in disordered solids. Physical Review E, 80 (4), 041503(1-11), 2009. DOI: 10.1103/PhysRevE.80.041503

  4. de Souza, VK and Harrowell, P. Rigidity percolation and the spatial heterogeneity of soft modes in disordered materials. Proceedings of the National Academy of Sciences, 106 (36), 15136-15141, 2009. DOI: 10.1073/pnas.0901112106

  5. Ping, W; Harrowell, P; Byrne, N and Angell, CA. Composition dependence of the solid state transitions in NaNO3/KNO3 mixtures. Thermochimica Acta, 486 (1-2), 2009. DOI: 10.1016/j.tca.2008.12.017

  6. Miracle, DB and Harrowell, P. Noncrystalline compact packings of hard spheres of two sizes: Bipyramids and the geometry of common neighbors. Journal of Chemical Physics, 130 (11), 114505, 2009. DOI: 10.1063/1.3082008

  7. Petravic, J and Harrowell, P. Spatial dependence of viscosity and thermal conductivity through a planar interface. Journal of Physical Chemistry B, 113 (7), 2059-2065, 2009. DOI: 10.1021/jp807254b

  8. Widmer-Cooper, A; Perry, H; Harrowell, P and Reichman, DR. Irreversible reorganization in a supercooled liquid originates from localized soft modes. Nature Physics, 4 (9), 711-715, 2008. DOI: 10.1038/nphys1025

  9. Kummerfeld, JK; Hudson, TS and Harrowell, P. The densest packing of AB binary hard-sphere homogeneous compounds across all size ratios. Journal of Physical Chemistry B, 112 (35), 10773-10776, 2008. DOI: 10.1021/jp804953r

  10. Hudson, TS and Harrowell, P. Dense packings of hard spheres of different sizes based on filling interstices in uniform three-dimensional tilings. Journal of Physical Chemistry B, 112 (27), 8139-8143, 2008. DOI: 10.1021/jp802912a

  11. Alcaraz, AN; Duhau, RS; Fernandez, JR; Harrowell, P and Miracle, DB. Dense amorphous packing of binary hard sphere mixtures with chemical order: The stability of a solute ordered approximant. Journal of Non-Crystalline Solids, 354 (27), 3171-3178, 2008. DOI: 10.1016/j.jnoncrysol.2008.01.004

  12. Petravic, J and Harrowell, P. Equilibrium calculations of viscosity and thermal conductivity across a solid-liquid interface using boundary fluctuations. Journal of Chemical Physics, 128 (19), 194710, 2008. DOI: 10.1063/1.2911924

  13. Ediger, MD; Harrowell, P and Yu, L. Crystal growth kinetics exhibit a fragility-dependent decoupling from viscosity. Journal of Chemical Physics, 128 (3), 034709, 2008. DOI: 10.1063/1.2815325

  14. Petravic, J and Harrowell, P. Erratum: On the equilibrium calculation of the friction coefficient for liquid slip against a wall (vol 127, art no 174706, 2007). Journal of Chemical Physics, 128 (20), 209901, 2008. DOI: 10.1063/1.2925797

  15. Petravic, J and Harrowell, P. On the equilibrium calculation of the friction coefficient for liquid slip against a wall. Journal of Chemical Physics, 127 (17), 174706, 2007. DOI: 10.1063/1.2799186

  16. Jabbarzadeh, A; Harrowell, P and Tanner, I. The structural origin of the complex rheology in thin dodecane films: Three routes to low friction. Tribology International, 40 (10-12), 1574-1586, 2007. DOI: 10.1016/j.triboint.2006.11.003

  17. Jabbarzadeh, A; Harrowell, P and Tanner, RI. Crystal bridges, tetratic order, and elusive equilibria: The role of structure in lubrication films. Journal of Physical Chemistry B, 111 (39), 11354-11365, 2007. DOI: 10.1021/jp0725578

  18. Hudson, TS and Harrowell, P. A systematic enumeration of local topological relaxation mechanisms in amorphous networks and their efficiency in network relaxation. Journal of Chemical Physics, 126 (18), 184502, 2007. DOI: 10.1063/1.2724819

  19. Widmer-Cooper, A and Harrowell, P. On the study of collective dynamics in supercooled liquids through the statistics of the isoconfigurational ensemble. Journal of Chemical Physics, 126 (15), 154503, 2007. DOI: 10.1063/1.2719192