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Chemistry experiments on the computer instead of the bench top

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Chemistry experiments on the computer instead of the bench top

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Philippe Aeberhard

Posted on 22 September 2011

Estimated read time: 4 min
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Chemistry experiments on the computer instead of the bench top

Posted by s.hettrick on 22 September 2011 - 11:31am

Fireworks.jpgToday, we start publishing blog posts from our new Agents. First up is Philippe Aeberhard, who takes a look at how software is helping investigate experiments that are difficult, dangerous and expensive to perform in the laboratory.

Fire, smoke and spectacular effects make up much of the fascination that led many chemistry students to their discipline. But it is these same aspects that can make everyday life for the (grown-up) chemical sciences researcher more difficult: considerations for workers' health and safety make experiments under harsh conditions cumbersome to carry out. Experiments involving very high pressure as encountered in geochemistry, or extremely high temperatures to which nuclear fusion materials are exposed, usually require expensive equipment. A research laboratory for conducting explosives research, for example, requires a sophisticated setup to prevent unwanted explosions and to protect workers. Similarly, the equipment for investigating the properties of materials under extremely high pressures like those found in the inner core of earth - more than 3,000 times higher than at the deepest point of the Oceans - presents a substantial cost.

Chemists focusing on materials and compounds under extreme conditions need not despair: a good part of the work can safely be conducted on a computer. In 2001, researchers concluded from atomic simulations that if titanium oxide, a very abundantly used semiconductor, is put under high pressures, it will undergo a change in atomic structure and transform into a material nearly as hard as diamond (the hardest known material) making it the "hardest known oxide". This theoretical experiment was subsequently reproduced in the laboratory, where the researchers compressed titanium dioxide in a diamond anvil cell, which is a device capable of putting a material under extremely high pressure. The structure predicted by computer modelling and termed Cotunnite titanium dioxide was indeed obtained, and its extreme hardness matched the prediction. The results were published in the journal Nature, and represent one of the earliest examples of a successful chemical experiment based on a computational prediction. Computer simulations had thus far been a discipline on its own, relying on results from experiments to verify the models used.

This new trend has been made possible by the development of ever more powerful high-performance computing systems and more and more accurate and efficient simulation software. An increasing number of results are being published that exemplify materials development by computational screening, where a new material with desired properties is first simulated on the computer before, possibly expensive, attempts are made at synthesising the material in the laboratory. Based on the discovery of Cotunnite titanium dioxide, Japanese researchers from Ehime University have recently discovered another new titanium dioxide structure at even higher pressure by computational screening and subsequent experimental verification. This material has remarkable optical properties, quite different from other forms of titanium dioxide. In drug discovery, the development cost of a new drug can be reduced by performing the initial assays on the computer in the search for active compounds.

While computer simulation software has improved substantially, simulations can never be a complete substitute for experimentation in the laboratory, but they can reduce the number of attempts and the time spent, or effectively wasted, on investigating unsuccessful routes. The fascination with fire and smoke is therefore unlikely to be replaced by a passion for computer science in attracting students to chemistry.

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