The formation and transformation of minerals in nature tend to happen slowly, in geological time. Or they require conditions such as very high pressure or high temperature, or particular chemical environments. There are a lot of questions about the chemistry that drives these processes.
If my work can shed light on the actual chemical reactions that drive some of these processes, I can contribute to an understanding of how we might make mineral processes happen artificially – perhaps even mimic them to help solve our environmental challenges.
We know a lot about how minerals form and their role in our environment. But we have lots of questions. How do minerals interact with their chemical environment? How do they dissolve and regrow into other materials? And how do living beings influence the formation of minerals?
Some plants grow minerals in particular spiky shapes to protect themselves from herbivores. If you eat those plants you either die or get an upset stomach. Either way, you will not eat them again.
In coral reefs, we have sea-life growing minerals as part of their skeletons. Even our human bones are made of calcium phosphate with an organic component, so that’s basically a mineral. Here, there is an equilibrium of continuous formation and dissolution, but if you perturb this equilibrium for some reasons, things change. For example, in osteoporosis the dissolution of the bones becomes faster than their growth, which is why the bones become weaker. So there is a lot of mineral chemistry happening in living beings. And it’s very interesting chemistry.
If we can understand how living beings form minerals with specific shapes, textures and compositions, we might be able to design new materials for specific functions.
If we can understand how living beings form minerals with specific shapes, textures and compositions, we might be able to design new materials for specific functions. If we could, for example, grow something like a sea shell with the same level of accuracy that the sea creature does, we would open an entire new field designing new materials for applications in medical science or other similar technologies.
At a chemical level, atoms are a bit like Lego. You have pieces of different sizes and colours. Depending on how you combine them, you can come up with a boat or a house or a castle. Mineral chemistry is the same. It’s just a matter of understanding how nature plays with it.
I have always had a natural aptitude for maths and science. Together with writing, they were always my favourite subjects at school. Then, when I was 12, a teacher showed us how molecules of water organise when transitioning from ice, to liquid, and then to vapour – they spoke about how energy was involved in the transition between states. I remember coming home, opening my textbook to the periodic table of elements, and memorising as many of them as possible – and their symbols. It was the day I became fascinated with chemistry.
So I had no doubt about what to choose at university. But I had no interest at all in computers – until towards the end of university, when I realised that theoreticians don’t do things with pen and paper. I learnt that if you want to do anything meaningful in the field of chemistry that fascinated me – theoretical chemistry – the only way to do it is through developing codes and using computers or supercomputers, depending on what you need to do.
At a chemical level, atoms are a bit like Lego.
I’m still not passionate about the computing itself. But I’m passionate about what computers allow us to achieve in all the sciences, and in chemistry in particular.
There are a lot of things you can do on a laptop – like simple tests and data analysis. But the vast majority of my calculations need computers as big as a room. It’s like having thousands of computer laptops all working together, with each laptop solving a tiny bit of the calculation. And then they combine everything into one answer.
For this reason, I am a massive user of our two national supercomputing facilities at NCI (National Computational Infrastructure at ANU, Canberra) and at the Pawsey Supercomputing Centre in WA.
Theoretical modelling offers several advantages. For example, you can design and test let’s say 1000 different chemicals, and see which are the most likely to form or which ones have the properties we are interested in, allowing us to exclude a certain number of possibilities without having to go in the lab and physically make all 1000 of them. There are also circumstances where experiments have limitations and cannot find out what atoms are doing or measuring certain quantities. This is when accurate theoretical models can be used to access details that you could not see or measure with an experiment.
There are processes that happen in nature that are exactly what we are looking for to address our environmental challenges.
For example, my group is trying to understand how minerals can capture carbon dioxide from the atmosphere. We know this happens because we see it in nature, and there are ways to make it happen artificially, but we are missing a lot of pieces of this chemical puzzle.
With computational methods, you can actually go inside a mineral and see what happens between the atoms – for example, how a molecule of carbon dioxide gets close to the surface of the mineral, kicks out the water that is “wetting” the surface, and then attaches and reacts. Under what circumstances can this happen? What is the step that we need to act on to speed up this process? This can be hard to capture from a physical experiment, but with modelling you can see it.
There are processes that happen in nature that are exactly what we are looking for to address our environmental challenges. But we miss several pieces of nature’s puzzles, and many of these are related to chemistry. I hope my work contributes to our understanding of how these processes work.
As told to Graem Sims.