Dr Deborah Crittenden
Position
Lecturer
Qualifications
BSc(Hons), PhD(University of Sydney)
Field of Study
Theoretical and computational chemistry
Room
738
Contact Details
Telephone: +64 364 2875
Fax: +64 3 364 2110
Email: deborah.crittenden@canterbury.ac.nz
Background
Deborah began her scientific career as an experimental biochemist and part-time computational chemist, during her Honours year in 2001. During her doctoral studies, she quickly discovered that computers were more reliable than biological systems, and changed research focus to graduate from the University of Sydney with a PhD in theoretical and computational chemistry in 2005. Since then, she has been working as a postdoctoral fellow with Professor Peter Gill at the Australian National University, developing new electronic structure models to capture electron correlation energies. She is looking forward to joining the Department of Chemistry at the University of Canterbury in early 2010.
Undergraduate Courses
(tba)
Graduate Courses
(tba)
Research Interests
My research interests lie in the development and application of new theoretical methods and algorithms for predicting the structure and dynamics of large and/or complex biological and supramolecular systems. These include:
- Intracule Functional Theory
The first tool any computational chemist needs is a way of calculating the energy of a system in any given configuration. Traditional quantum chemistry methods are either too expensive (wavefunction methods) or too inaccurate (density functional theory) to apply directly to large biochemical systems. Intracule functional theory aims to fill the gap between the complexity of all-electron wavefunction methods and the simplicity of one-electron density functional methods by extracting the electron correlation energy from the Omega intracule, a distribution function that gives the probability of finding two electrons separated by a certain distance u, moving with a given relative speed v and orbiting in a manner defined by the dynamical angle w.
The Wigner intracule for Beryllium contains only information about relative distances
and momenta from the original Omega intracule
- Quantum Monte Carlo methods
Nuclear vibrational motion often plays an important role in a variety of chemical, biochemical and physicochemical processes, but is often neglected or treated poorly due to the computational complexity and expense involved in its computation. I am interested in developing and applying simplified quantum nuclear dynamics models that focus in on only the dynamically important vibrational modes of complex systems e.g. torsional motions in proteins, intermolecular rearrangements in clusters.
Snapshots from high probability density regions of the nuclear vibrational wavefunction for CH5+, a fluxional molecule which exhibits complete proton scrambling even at zero Kelvin
- Proton-coupled electron transfer
Proton-coupled electron transfer reactions are the key step in photosynthesis, the mechanism by which light energy is harvested from the sun and converted into the chemical energy that is used to sustain life on earth, making them the most important in the biosphere, if not the world. However, to date, surprisingly little is actually known about the precise mechanism by which proton-coupled electron transfer reactions actually occur. I am particularly interested in developing and applying new quantum chemical methods that are capable of describing coupled nuclear and electronic motion.
Top down view of bacteriorhodopsin, the simplest known photoreceptor complex
- Solvation and environmental effects
It has been postulated in the scientific literature that the extraordinary catalytic ability of some biological enzymes is due to proton tunneling, which is facilitated by substrate binding in the enzyme’s active site. Similarly, intramolecular proton transfer can significantly change the properties of a molecule depending on its environment. An extreme example of this is the amino acid glycine, which is uncharged in the gas phase but zwitterionic in aqueous solution. Properly describing this effect requires an accurate but efficient method for calculating the energy of both the charged and uncharged forms of the solute or substrate, along with a realistic solvation model and a sophisticated treatment of nuclear motion.
Solvated glycine zwitterion from density functional theory based molecular dynamics simulations
Research Group Members
Wanted.