theoretical studies in physical chemistry



I am interested in understanding the ways collective order can occur among large numbers of interacting atoms or molecules and what kind of motions these dense phase can exhibit. While most of these projects involve some level of computer programming, no experience with computers is assumed.

Project 1

Modelling the precipitation of calcium carbonate

The precipitation of calcium carbonate is a crucial process in biomineralization and geological deposition. Modelling ionic precipitation from aqueous solutions is difficult due to the long range interactions and the need to include many water molecules. The goal of this project is to develop model potentials for the interaction between Ca2+ and CO32- that are short range, include the average effect of the water and can still capture the relative stabilities of the solid phases of the carbonate.


Project 2

How do liquids crystallize? (with Toby Hudson and Asaph Widmer-Cooper)

Crystallization of a liquid involves two kinds of organization: local ordering of molecules and the alignment of these local ordered regions to form the extended crystal. In one project you will use computer modelling to understand why some chiral molecules crystallise as pure ennatiomers while other prefer to form racemic crystals. Recent results in our group and overseas have revealed that a number of liquids manage the local ordering well before any long range alignment occurs. In this project you will develop a simple model of this two stage ordering and explore the kinetics of nucleation when the rate limiting step is long range alignment.


Project 3

How do solids flow?

The distinction between a solid and a liquid is one of our most basic classifications and, yet, the distinction is no where so clear cut. Highly viscous liquids and soft solids blur the boundaries. In this project you will use computer simulations to ask how does a disordered glass become rigid and what are the microscopic mechanisms by which a glass can flow when sufficient stress is applied.

 

  


Project 4

Molecular walkers

Through the interplay between molecular shape and the structure of the substrate surface, we can control how an adsorbed molecule ‘walks’ across the surface. Modelling projects on this topic include developing rapid ‘loping’ gaits using flexible chain adsorbates and developing an artificial nose based on the differential adsorption coefficient of a small set of surface structures.


Project 5

Simulations of self assembly
The spontaneous development of order is a central ordering principle in living things and a perennially surprising outcome of combining molecular interactions and thermal fluctuations. A fundamental form of assembly that remains poorly understood is the spontaneous stabilization of surfactant micelles in non-polar liquids – so called reverse micelles. In this project you will build on previous work in the group to simulate reverse micelles and establish the physical origin of this order.



For further information, please contact:

Professor Peter Harrowell

Room 314

School of Chemistry

Eastern Avenue

University of Sydney NSW 2006

Phone: +61 2 9351 4102

Email peter.harrowell@sydney.edu.au