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Forrest Scholar Liam’s electron-molecule collision modelling ‘great step forward’ in largest nuclear fusion experiment the world has ever seen

12 June 2020
By Liz McGrath

Put Liam Scarlett to the ‘pub test’ and ask him to summarise his area of research in 30 seconds and no problem. That’s despite his field of theoretical physics being one of the most intellectually demanding in science.

“I use supercomputers and quantum mechanics to study atomic and molecular collisions,” the 28-year-old Forrest Scholar says simply.

“We work on the theory side of the reactions that take place when subatomic particles and molecules collide with each other – we model the reactions and predict the outcomes.

He might make it sound easy, but during his PhD Liam has successfully advanced the field of molecular collision physics by devising new theoretical methods, developing massively-parallel computer codes and using Western Australia’s Pawsey supercomputing facilities to perform large-scale scattering simulations.

As part of that work, he’s developed a new computational method known as vibronic close-coupling for modelling collisions of electrons and positrons with diatomic molecules.

The method is based on the first principles of quantum mechanics and doesn’t apply the approximations utilised in previous research, which allows Liam to perform the most accurate calculations in the world for molecular collisions.

Quite an achievement for the Fremantle-born scientist who admits he was far more interested in music than science at secondary school!

I was late to physics and to discovering science at all

“We are a musical family,” Liam smiles. “Both my parents are recreational musicians, and Mum is a piano teacher. You could say I had a bit of a windy journey to discovering physics.”

That ‘long and winding road’ (to borrow from Paul McCartney) started with a year studying music at the Western Australian Academy of Performing Arts, or WAAPA, after secondary school at South Fremantle Senior High School (now Fremantle College) followed by a period studying psychology at Murdoch University.

“It was during my psychology degree that my interest in science began,” he recalls. “I’d started reading Richard Dawkins and watching Carl Sagan documentaries and, in a similar way that they’ve inspired many people before me, I was intrigued.

“As part of my psychology degree I had to do a mandatory course in mathematics. To my surprise I was quite capable, which gave me the confidence to pursue my interest in physics.”

Signing up for a Bachelor of Science and then Honours in Physics at Curtin University in 2014, Liam says in one of those synchronistic life changing moments, he was also introduced to a research group that would change his future.

Directed by world-leader in the field of atomic collision theory Professor Igor Bray, the Theoretical Physics Group is internationally known for its work on electrons, positrons, photons, and heavy particles scattering from atoms, ions and molecules, as well as laser and atom-surface interactions.

“I owe everything to this research group, they’ve been incredibly supportive and have provided me with great mentorship,” Liam says. “They’ve been leading the field for the past three decades, they’ve published papers that are older than I am!”

Liam Scarlett at the Sphinx lookout on Magnetic Island (Townsville) during the 2018 Gaseous Electronics Meeting.

Atomic and Molecular Collisions and becoming a Forrest Scholar

At the end of 2017, and with “zero expectation of success”, Liam received another major boost to his career when he was awarded a Forrest Research Foundation Scholarship, designed to support outstanding domestic and international students as they complete their PhDs.

“I applied and didn’t think I’d get it and then I did – it’s been completely life changing,” he says. “It’s allowed me to live at Forrest Hall and it’s been fantastic having access to all the resources the scholarship provides to conduct our research. I feel incredibly lucky.”

And for the future? So far, Liam’s calculations have produced data for over 58,000 possible reactions in electron collisions with molecules of hydrogen and its isotopes, the most comprehensive and accurate dataset of its kind ever produced.

He’s designed an online database ( to make those results freely available to scientists worldwide, and with the support of the Forrest Research Foundation has promoted the research in numerous national and international forums.

The molecular collisions he models are fundamental processes that play a major role in a diverse range of fields including energy production, medicine and astrophysics. But the area he’s most excited about is nuclear fusion, and his research into electron-molecule collisions is already being used in one of the largest scientific projects in the world, the €20 billion International Thermonuclear Experimental Reactor (ITER) in France.

“Our calculations are being used to construct models for the plasmas which will be present in the ITER fusion reactor,” he explains. “These models will be used to perform vital diagnostics and improve the performance of the heating and waste-removal systems in the reactor.”

Scientists at the Max-Planck Institute for Plasma Physics (IPP) described the modelling made possible by Liam’s research as “a great step forward that we were awaiting for many years”. The collaboration between the IPP and WA will result in the world’s first ever complete collisional-radiative model for molecular species in fusion plasmas.

Pretty good going for a young man who wasn’t even sure he liked science back in secondary school.

Liam Scarlett presenting at the 2019 POSMOL conference in Serbia.

The future and a strumming guitar

All thoughts now are on the ITER experiment. “Once it’s completed, it will be the largest magnetic-confinement nuclear fusion experiment in the world,” Liam says. “Fusion reactors will be able to provide a safe and virtually limitless source of energy with no long-lived radioactive waste or carbon emissions.

“It’s a much safer alternative to the fission reaction utilised in present-day nuclear power where, as everyone knows, there’ve been some very famous examples of runaway chain reactions. One of the benefits of the fusion process is that runaway chain reactions are impossible, making it much safer.”

Liam says with more than 20 countries contributing, the ultimate aim is to demonstrate the feasibility of nuclear fusion energy, paving the way for the next generation of fusion reactors to be used for power production.

But he says, while COVID-19 has meant much more time working from home alongside partner Katie and the couple’s cat Priscilla, he’s also conscious that life can’t be 100 per cent numbers and calculations.

“Yes, I spend a lot of my time working on physics, but that’s not to say we don’t love stepping outside and taking some meandering walks along the river. And very occasionally I do pick up my guitar and strum a few tunes.”

That early love of music, it seems, hasn’t completely disappeared.