Think through your morning routine. Hopefully you brush your teeth. Maybe you take a multivitamin. You might turn on your flatscreen TV to watch the news, or check your messages on your iPhone.
Chances are Dalhousie Chemistry Professor Axel Becke has played a small role in making each and every part of that routine possible.
No, Dr. Becke isn’t a household name to most people, but among chemists he’s as well known as they come. He’s one of the most referenced researchers in the world, with more than 100,000 citations to his name so far. According to the journal Nature, two of his articles rank among the Top 25 most-cited papers of all time, across all scientific disciplines, evidence of how his work touches nearly every corner of the chemistry world.
It’s all due to his success in advancing a computational method called the “density-functional theory” (DFT) of electronic structure. Over an incredible 30-year career, Dr. Becke’s refinements have expanded the theory’s applications within chemistry to the point where today there are few chemical computations that don’t, in some way, make use of his work — from drug discovery to cleaner energy and everything in between.
A Herzberg honour
No stranger to awards and honours, Dr. Becke is receiving one of the most significant awards there is: the Gerhard Herzberg Canada Gold Medal for Science and Engineering, presented by the Natural Sciences and Engineering Research Council of Canada (NSERC).
He'll receive the award Tuesday evening at a reception at Rideau Hall with the Governor General.
The award, perhaps Canada’s most prestigious scientific research prize, was presented last year to another Dal researcher, molecular biologist Ford Doolittle. That was the first time the Herzberg Medal had been awarded to a researcher from Atlantic Canada; now Dalhousie can proudly boast back-to-back recipients.
“It’s a huge honour,” says Dr. Becke. “What’s great is that it’s awarded by the funding agency that’s supported me throughout my career, and to receive it towards the end of that career is really special.”
Russell Boyd, former chair of Dalhousie’s Department of Chemistry and someone whom Dr. Becke credits as a professional mentor, says the award reflects Dr. Becke’s global impact in his field.
“[His] seminal research in theories of electronic structure has led to major advances in chemistry, physics and materials science,” says Dr. Boyd. “Even NASA scientists employ Becke’s computational methods to support their space exploration programs.”
Faster, more accurate chemical calculations
Dr. Becke, who’s served as the Killam Chair in Computational Science at Dalhousie since 2006, has spent his entire career focused on one goal: making the density-functional theory (DFT) work for chemical reactions.
“It’s fast,” says Dr. Becke, explaining why DFT, which is used to calculate the motions of electrons in atoms, molecules and solids, has become the dominant method for modeling and simulating chemical systems.
“DFT is beautifully simple, beautifully intuitive and it’s much faster than the traditional non-DFT methods of calculating the properties of chemical systems. But to make it accurate, you have to crack the ‘Holy Grail’ of density-functional theory: the so-called 'exchange-correlation energy.'”
Easier said than done: when theoretical physicist Walter Kohn formally developed DFT in the 1960s (for which he shared the 1998 Nobel Prize in Chemistry with computational chemist John Pople), he identified a key energy term, the exchange-correlation energy, that cannot be easily calculated. “All of the chemistry is in that term, but there’s no exact expression for it,” says Dr. Becke. “So we have to model it, approximate it, and the approximations in the early 1980s were simply inadequate for good chemistry.”
In fact, at that time, DFT exchange-correlation models were far too crude to even calculate useful chemical bond energies — perhaps the most basic and foundational of chemical concepts. That’s where Dr. Becke started and, by the late 1980s, he had found viable functional forms that could accurately model the exchange-correlation energy for a wide variety of chemical reactions. The reach of his work expanded dramatically in the 1990s when his functionals were included in the most-used computational chemistry software packages in the world.
“At that point, nearly every chemist in the world could do DFT calculations,” he says.
Today, a theory that was once the domain of “a band of outsiders,” as Dr. Becke puts it, is used in more than 80 per cent of chemical computations. Scientists, engineers and companies around the world can model everything from simple molecules to complex biological systems and next-generation materials faster, and more accurately, than ever before — and it wouldn’t have been possible without Dr. Becke’s work.
An ongoing quest
Little wonder, then, that Dr. Becke’s CV is full of impressive honours. Last year, he received the Theoretical Chemistry Award of the American Chemical Society. Later this year, he’ll receive the Medal of the Chemical Institute of Canada. He’s a Fellow of the Royal Society of Canada and the Royal Society of London, a medalist of the International Academy of Quantum Molecular Science and the World Association of Theoretical and Computational Chemists, and a recipient of a Canada Council Killam Research Fellowship, to name a few.
His latest honour, the Herzberg Medal, comes with a $1 million research grant, the majority of which Dr. Becke is providing to the Faculty of Science to hire a new faculty member and researcher. Erin Johnson, currently a faculty member at the University of California, Merced, has been recruited to take up the new position this July, which will be known as the Herzberg-Becke Chair in Theoretical Chemistry.
“She’s an incredible theoretical and computational chemist, one of the best young theorists in the world,” says Dr. Becke of Dr. Johnson, and he would know: the two worked together at Queen’s University in the mid-2000s, where they developed novel DFT methods for dispersion (or van der Waals) forces, crucial for computations in biological chemistry.
Indeed, Dr. Becke’s work continues. Thirty years on, he’s still singularly focused on coming up with better and better approximations for the exchange-correlation energy.
“The number of problems that cannot be handled by DFT is getting smaller and smaller, but there are still corners of computational chemistry where DFT doesn’t work,” he says. “We’re looking for the universal density-functional theory that works for everything.”
“One of the qualities you need to really influence a field is perseverance — and I’ve had 30 years of perseverance on basically the same problem. We’re getting there. I can see the light at the end of the tunnel, but there’s still more work to do.”
We asked some of Dr. Becke's Dalhousie colleagues to share their appreciation for his work and a sense of its impact on the field of chemistry and beyond.
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