Theoretical and computational methods are used to study molecular interactions and quantum effects in chemistry.
My research examines the interactions within and between molecules in order to understand chemical reactivity and the relationship between structure and function in chemistry, biology and materials science. This work also involves close collaboration with a number of experimentalists, at Sydney and around the world. Over the last few years we have developed new quantum-based methods that can be used to determine molecular potential energy surfaces and enabling the simulation of chemical reactions. Applications include photochemistry, combustion, atmospheric chemistry, catalysis and nanotechnology.
Minimum energy structures and HOMOs for 4 possible sigma binding ligands
Roaming reaction dynamics (with Professor Scott Kable)
"Roaming" has been coined to describe a newly recognised class of reaction mechanism which bypasses the conventional transition state to a reaction. We have shown that roaming mechanisms are not limited to H atom roaming and may be much more widespread than initially thought. This project investigates the prevalence of roaming mechanisms and develops new theoretical techniques to describe them.
Techniques previously developed for molecular potential energy surfaces are applied to other property surfaces (such as dipole moment surfaces) and to non-metallic crystals such as silica, zeolites or metallo-organic framework materials (MOFs). These property surfaces allow, for example, the modelling of the response of a molecule to an inhomogeneous environment, like a protein binding site, or the prediction of the ro-vibrational spectrum of a molecule, or the structures and properties of a crystal.
Equillibrium structures for one, two and threeadsorbed H2 molecules
Novel hydrogen storage materials
The nature of physisorbed H2 within novel MOFs is examined. Small cluster models are developed and then extended, using periodic boundary conditions, to allow us to design new materials with, ideally, H2 storage densities and binding energies appropriate for use as a fuel in vehicles. A particular project involves determining differences in the binding enthalpy of ortho- and para-H2 to our model systems, which are potentially observable in experiment.
The CH5+ system, chemistry's "Cheshire Cat", serves as the prototypical carbocation and its structure has been the subject of much controversy. C2H7+, however, is a more realistic prototype but is considerably more complex than CH5+. This project examines the transition from a "fluxional" to a "classical" structure, on deuteration, as well as temperature and nuclear spin effects in CH5+ and C2H7+.
Working with experimentalists, we have studied a number of biologically active molecules in order to develop an understanding of the key interactions involved in their action. This will allow pharmacaphore and QSAR models to be developed. In all these systems the environment, aqueous or protein, is crucial. We are currently developing new methods to model environmental effects in terms of external, inhomogeneous electric fields: the molecular response to the field is expanded as a power series in the field. In this way the zero field properties of the molecule can be used to build up a description of a range of different environments.
For further information, please contact:
School of Chemistry
University of Sydney NSW 2006
Phone: +61 2 9351 4420