The computer modelling techniques developed by Axel Becke, professor and Killam Chair in Computational Science at Dalhousie University, over the past three decades are now being used for a huge range of applications, from discovering drugs to developing nanotechnology to designing materials for use in clean energy technology.
Becke will be awarded the 2015 Gerhard Herzberg Canada Gold Medal for Science and Engineering for his work at a ceremony in Ottawa today, announced the Natural Sciences and Engineering Research Council, which is presenting the award. NSERC is Canada's main science and engineering funding agency.
The $1-million prize recognizes "sustained excellence and influence" in Canadian research that has "substantially advanced" science or engineering.
Becke helped make refinements to density-functional theory (DFT), which is used to predict the behaviour of the atoms that make up matter from the motion of their electrons — allowing chemists to run many experiments inside a computer to complement their work on the lab bench.
Contribution to Nobel Prize
The theory is so important to modern chemistry that in 1998, University of California, Santa Barbara chemist Walter Kohn shared half the Nobel Prize in Chemistry for first proposing the theory in the 1960s.
"Density-functional theory is applicable to anything and everything because all matter in our terrestrial world depends on the motion of electrons," Becke said in an interview with NSERC president Mario Pinto posted on YouTube.
But until the 1980s, he added, the theory wasn't accurate enough to be that useful.
"And I just wondered: How can we make it better?"
Becke estimates that his research helped improved the accuracy of the theory by "about a factor of 50."
According to NSERC, the fact that Kohn received the Nobel prize "was in large part an outcome of Dr. Becke's enhancements of the theory."
Becke was one of two early pioneers who ultimately made it possible for chemists to actually make use of Kohn's theory, said Dennis Salahub, a University of Calgary theoretical chemist who researches density functional theory and has known Becke for 35 years.
Paul Ayers, a McMaster University chemist who was one of the referees for the Herzberg award, said it's "difficult to overstate how monumental Becke's achievement was."
He greatly improved the accuracy of the theory by uncovering "deep insights" into how negatively-charged electrons swerve to avoid each other in molecules and materials, Ayers said in an email.
With those refinements, the theory allows computers to calculate how different atoms will bond together to form complex molecules, their "fingerprints" when probed with different analytical techniques, and how different molecules will interact with one another.
That can often help researchers decide what experiments to run in the lab, and to identify mystery molecules and processes they find in their experiments.
The fact that the calculations agree so well with what chemists find in the lab is "the reason we know it's a good theory," Salahub said.
Insights into things that can't be measured
In fact, the technique can even be used to see things that we can't measure using any existing techniques, such as how large proteins move and interact at a molecular level, he added.
"And then you can go even further into gaining insight into how nature works."
Decades ago, when theoretical chemists and physicists were first trying to predict the behaviour of atoms based on quantum physics — which governs the behaviour or very small particles like electrons – they used to painstakingly consider the motion of each individual electron, which was very complicated.
Kohn showed that wasn't necessary — you just needed to know the average number of electrons at any given point in space — that is, their density. That's why the theory is called density-functional theory.
That was far simpler than calculating the motion of each electron, and could be easily measured using x-rays, Salahub said.
The simplification eventually made it possible to use the theory to make predictions about the chemistry of very large molecules or complex systems — but not until Becke took that technique and incorporated important details about electron behaviour.
The refined theory has now been incorporated into software packages and used by scientists, engineers and companies around the world across a huge spectrum of scientific research.