Developing DL_POLY Molecular Dynamics Simulation code to tackle challenging problems in science and technology

Molecular dynamics (MD) simulation is an important tool widely used nowadays to understand the properties of many systems, alongside with experiments and theory. In several important applications, it is necessary to simulate systems of very large sizes approaching a micrometer. At these scales, many important physical processes operate that could not be studied before in MD simulations. Importantly, these processes include radiation damage effects due high energy recoils in materials used to encapsulate nuclear waste and in future fusion reactors. The research into these processes is currently very topical, as the UK government as well as others realise the importance of energy-related and environmental research.Recent advances in MD simulations and the availability of the cutting-edge high-performance computing, we are now in a position to simulate very large systems. However, there are several important obstacles related to our ability to efficiently run and analyse the results, and to turning these recent advances into an operational and useful simulation tool. One important problem is that the traditional way of writing out the trajectory file is no longer feasible due to the impractical file sizes generated and writing to disk times. Another problem that is specific to radiation damage simulations is that our current general-purpose MD code, DL_POLY, does not capture the essential physics of the process, electronic energy loss.This proposal aims at removing these obstacles by developing our high-performance MD DL_POLY code. We will develop the code to analyse many important physical properties on the fly, thus avoiding the need to operate with files of impractical sizes. We will also implement the recent algorithm of the electronic energy losses as a new general feature of the code. This will enable us to run radiation damage simulations of high energy operable in materials that are currently considered as encapsulation matrices for nuclear waste and in materials to be used in future fusion reactors. As a result, we will obtain physical insights into the impact of radiation damage on material performance. In combination with experiments by our project partners, the results of our MD simulations will provide for the predictive models of materials behaviour under irradiation and establish physical implications for the future applications of these materials.Apart from the benefit to the academic and industrial community working in the area of energy and environment, the results of our research will be important to a wider community of MD simulations. This community will benefit from the new features of the MD code capable of running and analysing the results of very large systems.

In summary, the impact will consist of several main components: (a) The results of this project will have an impact on the academic and industrial community researching into the radiation damage effects in materials used for the encapsulation of nuclear waste and materials in fusion reactors. These researchers will obtain the developed HPC DL_POLY software enabling them to run and analyse the effects of radiation damage in a range of materials of interest; (b) Using the developed HPC DL_POLY code, we will perform MD simulations of very high energy in several important materials, and discuss the obtained results and implications in publications and using other pathways. The academic and industrial community will benefit from the new results that we will obtain. In combination with experiments carried out by our project partners, the results of our MD simulations will provide for the predictive models of materials behaviour under irradiation. In points (a) and (b), the impact will be eventually linked to the economic and societal changes, through the safe encapsulation of nuclear waste and corresponding reduction of the risk of environmental hazards, the associated sustainability of carbon-free nuclear energy and to the feasibility of future fusion energy which the holds the promise of making a large difference to the supplies of green energy. In addition, the impact on the safe encapsulation of hazardous highly-radioactive nuclear waste will have important implications for public health, environmental protection, the quality of life as well as national security. Therefore, this research will impact on policy makers in these important areas. In the UK in particular, energy and environment are the energy and environment are the long-term priority areas for funding by the government, including by EPSRC and other Research Councils. The advances in these areas will therefore lead to the economic competitiveness of the UK. (c) We will implement several features in the HPC DL_POLY code that will have an impact on a general community involved in MD simulations beyond radiation damage. These features will be used to calculate several important physical properties of very large systems on the fly. DL_POLY is a flagship MD code in the UK, available for free to the UK academic users and to all other users for a small fee. Since 2006, DL_POLY has had 5760 license registrations and 583 of those were from the UK. In 2009, DL_POLY has acquired 165 UK licences. The licence holders include both academic and industrial users. The latter include large industries such as Shell and Pfizer. The outcome of this proposal will therefore have a quick impact on industry. As well as in points (a-b), the impact of this component will eventually translate into the socio-economic impact in terms of better understanding technologically important materials and systems and their use for the benefits of the economy and society. Finally, the post-doc on this project and a PhD student we propose to involve (with funding already secured) will acquire important skills enabling them to contribute to the currently important areas of energy and environment.