Research Fellows Directory
Dr Livia Bartok-Partay
University of Reading
A phase diagram shows the properties of a given material at specific conditions, for example, tells whether a substance is found as gas, liquid or a given solid structure at a particular temperature and pressure. It also shows when these phases transform into each other, corresponding to phase transitions. It is of great technological importance to have a complete picture of the phase diagram, however, performing and evaluating experiments can be time-consuming and expensive, or even impossible under extreme conditions, such as at pressures a billion times higher than atmospheric pressure or at temperatures high enough to evaporate metals. To overcome these difficulties, computer simulation techniques became widely used in studying phase diagrams. Nonetheless, the main difficulty in using computer simulations is that the number of possible ways atoms can be arranged in space is enormous, and no technique is capable of considering all of them, hence we need sampling.
In the past years I have been working on a novel computational technique, called nested sampling, which automatically generates all relevant configurations, and determines their stability relative to each other. It does not require advance knowledge of the studied system, and therefore it can be used in a fully automated way. More efficiency and more automation will let us do 'high-throughput calculations' and help to address scientific problems from a completely new aspect, making nested sampling a powerful tool for predicting phase diagrams.
I am planning to calculate the extreme high pressure phase diagrams of important materials, such as iron, which, for example, will aid the understanding of the structural properties of the core of the Earth. Alloys are widely used in industrial applications as their properties are often superior to those of the pure components. Nested sampling could make a large impact by aiding the design process of such multicomponent systems.
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