Partnerships The virtual laboratory
Supercomputers can be used to simulate materials at vastly diverse scales, from the flow of air past an aeroplane’s wing down to the movement of electrons around
individual atoms. Different length and time scale domains provide different levels of information, but little is currently known about how these levels of information are connected. Professor Peter Coveney of University College London has been
spearheading a long-term programme that aims to connect the scales, relating the behaviour of atoms and molecules to tangible properties at the macroscale
I
n the late 1980s, researchers from Toyota demonstrated that by reinforcing polymers such as nylon with clay at the nanoscale, a significant improvement in a wide range of engineering properties could be made.
Known as clay-polymer nanocomposites, these materials have very low density but are also tough and strong – ideal properties for the building of vehicles. Extensive research into these materials has been
going on ever since, and although there has been some success in finding useful new composites, it has proven to be difficult. The same researchers who made the initial discovery when working for Toyota recently wrote about the relative scarcity of such discoveries since their breakthrough almost thirty years ago, citing the laborious trial and error nature of the exploratory experiments required, but also a fundamental lack of understanding of how and why materials such as clay-polymer
nanocomposites anomalous properties. possess such Figure 1:
A snapshot from simulation of a self assembled stack of clay layer and polymer molecules
“By connecting all the scales together into a multiscale model, we were able to show the process of polymers getting inside the clay layers – how it happens and how long it takes”
Professor Peter Coveney of University College
London, in collaboration with his colleagues Dr James Suter and Dr Derek Groen, has been working on ways of connecting different representations of matter together, which he believes is the first step towards speeding up the process of discovering
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new and useful materials. “Imagine, for example, a material that has fractured. At the molecular level, this is shown as the breaking of chemical bonds by electrons moving between atoms, whereas the manifestation on a larger scale would be the breaking of a component made of that material. These are very different representations of the same event, but both are equally correct. To simulate this event separately at different scales is relatively easy. What is not so easy is to connect the two – to extrapolate the macroscale properties of a material from its chemical composition.” Creating a description of a material that works at all
scales without having to inject ad hoc parameters at higher
levels is a crucial step towards in silico
materials discovery. To pull off “multiscale modelling”, as it is known, the lowest level parameters must be extremely precise, and the most powerful computers are needed in order to run the simulations. But the rewards for succeeding in this task are great; if one can predict the useful physical properties of a material
from its molecular structure, then costly Insight Publishers | Projects
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