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­ncertainty Gives Scientists New Confidence in Search for Novel Materials


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The results of calculations aimed at determining which of six chemical elements would make the best catalyst to promote an ammonia synthesis reaction.

Researchers have developed a new method to estimate uncertainties in computer calculations used to facilitate the search for new materials.

Credit: Andrew Medford and Aleksandra Vojvodic/SUNCAT, Callie Cullum

Stanford University and SLAC National Accelerator Laboratory researchers have developed a method to estimate uncertainties in computer calculations that are used to facilitate the search for new materials.

"As more and more researchers use computer simulations to predict which materials have the interesting properties we’re looking for--part of a process called 'materials by design'--knowing the probability for error in these calculations is essential," says SLAC professor Jens Norskov.

The new method is based on Density Functional Theory (DFT), which predicts bond energies between atoms following the laws of quantum mechanics. DFT calculations enable researchers to predict hundreds of chemical and materials properties. However, since the researchers use approximations to simplify the calculations, each of the calculated material properties could be off by a considerable margin. The researchers estimated the size of those errors by calculating each property thousands of times, each time tweaking one of the variables to produce slightly different results. The variation in those results represents the possible range of error.

"We could predict, for instance, that ruthenium would be a better catalyst for synthesizing ammonia than cobalt or nickel, and say what the likelihood is of our prediction being right," says Stanford researcher Andrew J. Medford.

From SLAC National Accelerator Laboratory
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Abstracts Copyright © 2014 Information Inc., Bethesda, Maryland, USA


 

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