Sustainable domain-specific software generation tools for extremely parallel particle-based simulations

This research project emerged from the EPSRC Sandpit on Extreme Computing that took place in Jan 2010. The sandpit process facilitated discussion between a group of chemists and civil engineers who all use particle-based numerical simulation approaches. The applications motivating these scientists' simulations vary greatly (from quantum mechanics to dam engineering), very different scales are simulated (atoms in some cases, mm sized sand particles in others) and the interactions between the particles are modelled in significantly different ways. However all of the methods have a common basis (they simulate particles and their interactions) and they all require implementation in a high performance computing (HPC) environment. In fact the similarities in the simulation approach mean that there are key common challenges to achieving effective HPC implementations. Recent and likely future developments in HPC are making massively parallel computations viable; consequently there is a real possibility of achieving a step change in the level of complexity and realism in these numerical models with huge impact on industry and society. However, at the same time, the increased complexity of HPC hardware poses a barrier to being able to fully harness this resource. Working with the chemists and engineers, two computer scientists developed a strategy to address these challenges. The proposed approach is to develop a new Particle Science Language (PSL) to act as a bridge between the scientists who are developing particle based models and the computer science required to implement them in a rapidly evolving HPC environment. The scientists and engineers will implement their physical models in this relatively simple PSL and an automatic code generation system then automatically generate optimized code to effectively run the simulations on high performance systems. The research strategy is to rapidly develop the first implementation of the PSL and prototype it on micron to millimetre scale Discrete Element Modelling (DEM) dynamics code. From this early foundation, we will develop the PSL, with the key objectives of demonstrating generality in the breadth of applications within the particulate dynamics domain and portability to multiple HPC architectures. A range of particle based methods (PBM) are currently used to simulate materials in chemistry, engineering, physics and biophysics. The 4 types of PBM considered directly in the proposed are molecular dynamics (MD), the ONETEP quantum mechanics-based program, discrete element modelling (DEM), and smoothed particle hydrodynamics (SPH). The overall research objective is to develop a sustainable tool that will deliver, in the future, cutting edge research applicable to applications ranging from dam engineering to atomistic drug design. Measureable achievements will also be made during the current project. In fact, we anticipate at least 3 physical science firsts in the project lifetime:(1) The first protein drug simulations that describe the entire protein-drug complex and solvent from first principle quantum mechanics.(2) The first rationalization, at an atomic level, of polymer solubility in CO2, with chemical accuracy. (3) Simulation of the vibrational spectrum of a carbon nanotube from first principles quantum mechanics.(4) Simulation of triaxial compression tests with 1,000,000 particles From a Computer Science perspective the project will lead to a novel high-level compiler optimisation framework that captures dependence, data distribution and loop nest optimisation in a context of highly-irregular data structures beyond the scope of classical approaches such as the polyhedral model, or even new results in shape analysis and ownership-type abstractions.

The project aim is to generate a step change in the level of realism that can be included in particle-based computer simulations. By enabling sustainable access to the best HPC hardware more sophisticated models of the particles and their interactions will be possible while simulating more particles for longer timescales. The project will deliver very high impact science across a range of length scales. We will develop a means for the physical scientists to focus on understanding their systems without having to exert effort in highly complex HPC code development. At the same time they will be able to directly exploit the latest computer science software technology research. Over the duration of the project and in the future the PSL will enable high impact basic research with many benefits for a range of industries and for society in general. Increasing realism makes the simulation of industrially relevant processes more relevant. Specific examples as well as the consequent benefits are listed below: 1. Engineering analysts: Both DEM and SPH can simulate understand failures such as erosion or landslides, and are useful developing methods to handle the flow of granular materials, amongst many other applications. 2. Industrial chemists using supercritical carbon dioxide: The understanding gained in simulation will enable carbon dioxide to gain more widespread use as a solvent. There are then health and environmental benefits as well as scope for commercial application. 3. Commercial uses of ab-initio MD: The ONETEP code (to be incorporated in the project) already has a strong commercial user base. There will be a significant increase in the scope to use this code for materials and drug development (e.g. by simulating vibrational spectrum of a carbon nanotube). PROJECT TEAM: This project is a new collaboration and there will be much cross-fertilization of information and skills. The research staff that will be taken on will all develop expertise in their specific area of work , however they will also develop their communication skills and a broader scientific understanding as a consequence of the interdisciplinary nature of the research. ACHIEVING IMPACT: Key to delivering benefits will be achieving the research objectives. This will be ensured by careful management of the project, a focus on maintaining the collaborations and recruitment of top quality staff. Workshops at each host university will bring a broader scientific community to the project. Journal publications and presentations at conferences will serve to disseminate the findings to the research community. Industry will be informed of progress via invitations to workshops, communication to existing industrial collaborators.