Using computer simulations to describe a mechanism for cosmic dust grain seed formation around carbon-rich stars
Observations from radio telescopes have determined that an envelope of dust surrounds certain stars. These particular stars emit more carbon and less oxygen than most other stars. Other work has accumulated evidence that polycyclic aromatic hydrocarbons (PAHs) exist in the interstellar medium. Since from terrestrial investigations, it is known that flames produce PAHs, a hypothesis has grown that around these carbon rich stars polycyclic aromatic hydrocarbons are synthesized in a manner similar to that occurring in flames.
As these molecules become larger the forces of attraction between the large molecules become sufficient to allow molecules to aggregate together in the prevailing temperature of 1000 K or a little less. In this project you will study the clustering of PAHs using molecular dynamics simulations (MD) and perform highly accurate ab initio simulations to investigate the interaction energy of these clusters. You will be using MD simulations to provide evidence of a mechanism of the aggregation to form heterogeneous clusters, which are made up of different polycyclic aromatic hydrocarbons. You will also be investigating the driving force of this aggregation mechanism by using ab initio simulations.
The results of this project will form the basis of a model that will provide evidence of how dust forms in outer space, which then go on to form larger celestial objects.
As part of this project the successful PhD applicant will:
- Determine the temperatures required for aggregation of polyaromatic hydrocarbons
- Understand the differences in the properties of aggregation between homogenous and heterogenous mixtures
- Understand the structure and stability of the particles
- Perform a series of large scale molecular dynamic simulations of polyaromatic hydrocarbons
- Perform a series of highly accurate ab initio calculations to determine the interaction energies of dimers and trimers
- Analyse the structures of these particles and understand the stability
- M. Thomas, I. Suarez-Martinez, L.J. Yu, A. Karton, G.S. Chandler, M. Robinson, I. Cherchneff, D. Talbi, D. Spagnoli, Atomistic simulations of the aggregation of small aromatic molecules in homogenous and heterogenous mixtures, Phys. Chem. Chem. Phys., 2020, Advance Article
I am a computational chemist and senior lecturer in the School of Molecular Sciences at UWA. My research is focused on the application of computer simulations to investigate the aggregation of polyaromatic hydrocarbons which have astrochemical and environmental implications.
- Dr Irene Suarez Martinez, Curtin University
- Dr Dahbia Talbi, Université Montpellier
How to Apply
- To be accepted into the Doctor of Philosophy, an applicant must demonstrate they have sufficient background experience in independent supervised research to successfully complete, and provide evidence of English language proficiency
- Requirements specific to this project:
- A bachelor’s degree with honours (or equivalent) in chemistry, physics or related disciplines.
- Experience with atomistic simulation software and working with a Linux operating system is desirable but not essential.
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