Software development for virtual e-collision experiments using high performance computers

电子与原子和离子的碰撞多年来一直是国际关注的主题。这些过程的数据对于分析许多科学和技术领域的重要物理现象至关重要。尽管这些应用的重要性，相对较少的准确的横截面数据是已知的许多过程中涉及。我们的研究的总体目标是开发一个精心设计和数字强大的软件系统，能够利用高性能的架构，这将使虚拟实验进行电子碰撞与氢和准单电子原子和离子在计算上具有挑战性的中间能量制度。这项建议将着重于重新设计和进一步开发Fortran软件套件2DRMP。这套由7个程序和大约20，000行代码组成的软件是经典R矩阵方法的新扩展，在过去的35年里，Burke和他的合作者在贝尔法斯特女王大学开创并构建了该软件。虽然2DRMP在推进基本电子碰撞物理学方面很有用，但它存在计算瓶颈，这阻碍了它在解决更具挑战性的物理学方面的性能。我们设计了一种新的计算策略，它比原来的实现更准确，更快。例如，在国家超级计算机HPCx上运行的原型2DRMP比原始代码快350倍，成本低25倍。为了保持英国在这一领域的领先地位，必须将原型转换为生产代码，并使用现代软件开发方法重新设计2DRMP，以达到高质量。由此产生的软件套件将更有效、更可靠和更易于维护。因此，将更容易增加新的建模功能，如模型势，相对论效应和光子化，并使软件适应不断发展的硬件架构。

Electron collisions with atoms and ions have been the subject of international interest for many years. Data from these processes are essential in the analysis of important physical phenomena in many scientific and technological areas. Despite the importance of these applications, relatively little accurate cross section data is known for many of the processes involved. The overall aim of our research is to develop a well-engineered and numerically robust software system, capable of exploiting high performance architectures, which will enable virtual experiments to be performed on electron collisions with hydrogen and quasi one-electron atoms and ions in the computationally challenging intermediate energy regime. This proposal will focus on re-engineering and developing further the Fortran software suite 2DRMP. This suite of seven programs and approximately 20,000 lines of code is a novel extension of the classic R-matrix method, software for which has been pioneered and built by Burke and his collaborators in the Queen's University of Belfast over the past 35 years. While 2DRMP has been useful in advancing fundamental electron collision physics it suffers from a computational bottleneck which impedes its performance in tackling more challenging physics. We have devised a new computational strategy which is more accurate and much faster than the original implementation. For example, a prototype 2DRMP running on the national supercomputer, HPCx, is up to 350 times faster than the original code and is 25 times less costly.To maintain the UK's lead in this area it is essential that the prototype is converted into a production code and that 2DRMP is re-engineered to a high quality using modern software development methods. The resulting software suite will be more efficient, more reliable and more maintainable. Accordingly it will be easier to add new modelling features such as model potentials, relativistic effects and photionization and to adapt the software to evolving hardware architectures.