“Spilady is a benchmark for material simulations”, says Sergei Dudarev, Head of the Materials Modelling Group at the Culham Centre for Fusion Energy (CCFE). With the help of EUROfusion’s Enabling Researcher Grant Chinese and European researchers created the Spin-Lattice Dynamics Simulation Programme. The unique software allows to model the behaviour of heated iron materials down to an atomic level. In fact, the fusion invention already raised interest in the information technology.

“Converting a scientific idea into something useful requires time, and the availability of time at the appropriate moment is often quite limited”, says Dudarev. It was ten years ago when Dudarev, and his colleague Peter Derlet from the Swiss Paul Scherrer Institute, first figured out that the traditional method of simulating materials, called molecular dynamics, is insufficient when it comes to modelling the behaviour of magnetic materials under a harsh environment.

Variety of material conditions

Before SPILADY, it was impossible to analyse the effect of magnetism on atomistic dynamic processes and on the thermodynamic properties of magnetic alloys. In fusion tokamaks, a strong magnetic field is used for the confinement of plasma. The steel components of a fusion reactor are exposed to such strong magnetic fields thus are expected to work at high temperatures. This affects the thermodynamic state of the steel and its response to mechanical loads.

Joining forces in Culham and Hongkong

The lack of a proper simulation programme also bothered Chung Ho Woo, a Chair Professor at the City University of Hong Kong and his associate Pui-Wai (Leo) Ma, who at that time was pursuing his PhD project. Ma, Woo and Dudarev accordingly joined forces and developed a code which has advanced atomistic simulations to a new level. They incorporated the effect of magnetism into the framework of molecular dynamics simulations. “But like any homemade code, it was not very userfriendly”, admits Duda rev. The grant from EUROfusion in 2014 finally enabled the main code developer Ma to write a new code, based on the developments that had occurred since 2007, and thus create a new simulation tool.

Spilady makes a difference

The programme now provides the basis for further steps of material simulation and testing, even beyond fusion research. Whenever magnetic aspects of material behaviour play a role, this programme might make a difference. “It can be used, for example, to investigate materials used for information storage, such as hard disks in computers”, adds Dudarev. In fact, a wellknown company which specialises in information technology has already knocked at Dudarev’s door. With their interest in modelling magnetic storage relevant alloys, the enterprise asked for a copy of SPILADY.

Seeking feedback from non-fusion applications

The British-Chinese team shares its software for free on a website. The colleagues are now hoping to encourage usage of the code and trigger feedback, especially from non-fusion applications. “This should help us to improve our models for steel at high temperatures”, hopes Dudarev.

Spilady can be downloaded here: http://spilady.ccfe.ac.uk

The construction of SPILADY serves Mission 3 of the European fusion roadmap: Neutron resistant materials. EUROfusion aims to develop materials which can withstand high heat and particle fluxes in structural materials of a fusion reactor. A software programme simulating such conditions, specifically designed to model fusion steels, helps assessing the lifetime of such materials.