The Atomistic Simulation Group headed by Professor Robin Grimes is based in the Department of Materials at Imperial College London. We use various simulation techniques to predict the atomic scale mechanisms and processes underpinning material properties in order to improve the understanding and design of new materials.

The group uses both quantum mechanical and classical pair-potential approaches to study various systems including:

  • Energy Materials:
    • Fuel cells.
    • Batteries.
    • Nuclear fuel.
    • Nuclear waste.
    • Fusion materials.
  • Semiconductors.
  • Glasses.

Latest News

ASG alumni Dr. Patrick Burr becomes a lecturer at the University of New South Wales in Australia

Former PhD and CNE student Patrick A. Burr was recently appointed Lecturer in Nuclear Engineering at the University of New South Wales (UNSW), Sydney, Australia. There, he coordinates and teaches on the MEngSci in Nuclear Engineering that was launched two years ago with the support of Robin Grimes and other colleagues from Imperial College’s Centre for Nuclear Engineering. The appointment is a joint position with the Australian Nuclear Science and Technology organisation (ANSTO), providing world-class nuclear research facilities.

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New Paper - "Simulations of Threshold Displacement in Beryllium"

Our new paper on the radiation damage of beryllium is now available:

  • M.L. Jackson, P.C.M. Fossati and R.W. Grimes, “Simulations of threshold displacement in beryllium”, Journal of Applied Physics, 120 (2016) 045903 doi:10.1063/1.4958974.

Atomic scale molecular dynamics simulations of radiation damage have been performed on beryllium to calculate the threshold displacement energy. A geodesic projection of displacement directions was used to investigate the orientation dependence of the threshold displacement energy with respect to crystallographic direction with unprecedented spatial resolution. It was found that the directionally averaged probability of displacement increases from 0 at 35 eV, with the energy at which there is a 50 % chance of a displacement occurring is 70 eV and asymptotically approaching 1 for higher energies. This is however strongly directionally dependent with a 50% probability of displacement varying from 35 – 120 eV, with low energy directions corresponding to nearest neighbour directions. A new kinetic energy dependent expression for the average maximum displacement of an atom as a function of energy is derived which closely matches the simulated data.

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New Paper - "Resolving the structure of TiBe12"

We are pleased to announce the publication of our new paper looking titanium beryllide a promising material for application in nuclear fusion applications:

  • M.L. Jackson, P.A. Burr and R.W. Grimes, “Resolving the structure of TiBe12”, Acta Crystallographica Section B, 72 (2016) 277. doi:10.1107/S205252061600322X.

A new family of intermetallics, Be12X (X = Ti,V,W,Mo) have been proposed to replace Be in nuclear fusion applications due to improved radiation tolerance and operating temperatures, the most promising of which is Be12Ti. In order to further investigate this material, we have first clarified the structure. There has previously been considerable controversy regarding the structure of TiBe12, which is variously reported as hexagonal and tetragonal. Lattice dynamics simulations based on density functional theory show the tetragonal phase space group I4/mmm to be more stable over all temperatures, while the hexagonal phase exhibits an imaginary phonon mode, which, if followed, would lead to the cell adopting the tetragonal structure. We then report the ground state elastic constants and temperature dependence of the bulk modulus and thermal expansion for the tetragonal phase.

Congratulations to Patrick Burr on Successfully Finishing his PhD

We would like to congratulate Patrick Burr in completing his PhD on Ab-initio modelling of Zr and Be alloys for nuclear applications. His work on zirconium alloys has identified a novel mechanism responsible for the microstructural evolution of nuclear fuel cladding due to irradiation. This knowledge may provide the basis for the development of improved Zr fuel cladding with higher radiation tolerance and corrosion resistance. At the same time, his work on beryllium alloys (used in satellite components and fusion reactors) showed that the mechanical and chemical properties of the metal may be improved by carefully alloying with small additions of Fe.

Read more about his thesis here page.

Say hello, wave goodbye...

Dr. Michael Cooper has now left the group to take up a position at Los Alamos National Lab in the United States. Throughout his PhD Michael did a sterling job in improving our understanding of the behaviour of spent nuclear fuel and actinide oxide systems in general and will be sorely missed. We’re sure he’ll keep up the good work in his new role across the pond and our best wishes go with him.

Secondly we would like to welcome our newest PhD student, Conor Galvin, who joins us from Imperial’s MSc in Nuclear Engineering. He will be picking up where Dr. Cooper left off, by considering the behaviour of mixed oxide nuclear fuels using atomic scale simulation.

Congratulations to Michael Cooper for recently completing his doctorate in materials research

We would like to congratulate Michael Cooper who was successful in the recent defence of his thesis entitled Atomic Scale Simulation of Irradiated Nuclear Fuel. His work focused on using static and molecular dynamics calculations to study the role of temperature and non-stoichiometry in conventional and advanced nuclear fuels. The project culminated in the development of a many-body potential model that was used to study the behaviour of mixed actinide oxide systems.

Dr. Michael Cooper
Dr. Michael Cooper

We are pleased to announce that Dr. Michael Cooper has given us permission to make his thesis available in PDF form on our theses page. Click here to access the thesis.

New Paper - "Effects of Gallium Doping in Garnet-Type Li₇La₃Zr₂O₁₂ Solid Electrolytes"

The accepted manuscript of our new paper on gallium doping in LLZrO battery materials is now available online:

Percolation Pathways in LLZrO

The paper is the result of an ongoing collaboration between the group and Dr. Randy Jalem. Randy originally spent several months with us at Imperial whilst visiting us as a PhD student from Nagoya Institute of Technology (Japan) and we would like to thank him and the other authors for all their hard work in bringing this to completion.

Research highlights:

  • LLZrO is a candidate for use as solid electrolytes in battery applications.
  • The effects of Ga doping on the structure are considered.
  • Ga is found to stabilise the cubic phase.
  • The connectivity of Li percolation networks in LLZrO are visualised.

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New Paper - "Thermophysical properties and oxygen transport in the (Uₓ,Pu₁₋ₓ)O₂ lattice"

Our latest paper is now available from the Journal of Nuclear Materials:

In this paper we build upon a recent body of work using a many-body potential approach (see potentials page) to investigate the thermophysical and diffusion properties of actinide oxides. Using an updated version of the PuO2 parameter set we have studied the thermal expansion, specific heat capacity, oxygen diffusion and the oxygen point defect energies of (Ux,Pu1−x)O2. The results shows that the non-uniform cation lattice has a much smaller effect on the oxygen diffusion in (Ux,Pu1-x)O2 compared to (Ux,Th1-x)O2. This is expained in terms of the lattice parameter missmatch between the end member oxides and the role this plays in the defect energies.

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Potential Update - Modification to PuO₂ parameters enabling the reproduction of the melting point

In this update to our actinide potential model, adjustments have been made to the PuO₂ parameter set that enable the potential to reproduce the experimentally observed melting point.

The new parameters are reported on the actinide potential website and have been used in a recent study on (U,Pu)O₂ mixed oxides that is accepted for publication in the journal of nuclear materials.

Visit the actinides potential page for more information.

Preprint of New Paper Now available: "From solid solution to cluster formation of Fe and Cr in α-Zr"

Our latest paper on alloying additions in Zr is now available as a pre-print on arXiv:

  • P.A. Burr, M.R. Wenman, B. Gault, M.P. Moody, M.Ivermark, M.J.D. Rushton, M. Preuss, L. Edwards and R.W. Grimes, “From solid solution to cluster formation of Fe and Cr in α-Zr”, arXiv preprint (2015). PDF

By combining ab-initio simulations with advanced experimental techniques we investigate the microstructural change of Zr alloys under irradiation Zr alloys are used as nuclear fuel cladding, and their integrity is crucial for the safe production of nuclear power. Of particular concern is the increase in corrosion that is observed when Fe and Cr particles (alloys additions) are dissolved. Dissolution of these particles is related to neutron irradiation, but the mechanisms by which this occurs is still unknown.

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