Improving the processing and performance of materials

New methods to better explain the behaviour of specialist materials

Research conducted in the Department of Mathematical Sciences (2006-13) has led to an improved awareness and understanding in the areas of thin film growth and in irradiated structural materials for nuclear power through the development of two new methods.

New methods to better explain the behaviour of specialist materials

The first method is an extension of an existing molecular dynamics method. A major problem with molecular dynamics is that it is suitable for modelling very fast processes that take microseconds, but much less suitable for slower processes such as thin film growth where the rate is measured in seconds.

To overcome this limitation, a new method has been devised in which the fast processes are calculated by molecular dynamics and the slower transitions are calculated adaptively using a different algorithm.

This method has been applied to the growth of thin films, giving guidance to industrialists as to the optimum conditions for growth. Extended time scale methods have also been applied to the modelling of radiation effects with applications in the nuclear industry.

The second area of work relates to Bader charge analysis which divides molecules into atoms. The research team developed an improved method currently used in conjunction with quantum chemistry software packages. The work also involved use of the Bader charge allocation in a unique way that enables the computation of large systems of atoms beyond the scope of numerical quantum calculations.

COST SAVINGS: The new method for modelling thin film growth has enabled Power Vision to use computer simulation to predict the type of optical thin film growth that will take place when certain parameters are varied –leading to cost savings through optimisation of the process.
IMPROVED PREDICTION OF AGEING EFFECTS: Investigation into the long term evolution of irradiated materials and dose effects in radiation damage studies has enabled the civil nuclear industry to improve the prediction of ageing effects in irradiated structural materials used in nuclear reactors and the behaviour of nuclear fuels. This has led to funding to optimise the safe disposal of nuclear waste.
SOFTWARE IMPROVEMENTS: The Bader charge algorithm has been incorporated into standard quantum chemistry software packages such as VASP and GAUSSIAN which are used by thousands of research scientists internationally, completely replacing previous techniques.
INFLUENCING POLICY: A member of the research team attended meetings with UK politicians and representatives of India’s Department of Atomic Energy, resulting in a change of UK Government policy towards nuclear collaboration with India with funding being made available for joint projects.