Materials and Molecular Modelling Exascale Design and Development Working Group

高性能计算机（HPC）或超级计算机，通过原子和电子结构建模，为理解、开发和越来越多地预测复杂材料的特性提供了令人兴奋的机会；随着硬件能力的增长，我们的计算技术的范围和能力也在不断扩大。百亿亿次系统的出现是这一演变的下一个戏剧性步骤。购买和运行这样一个系统的成本都很高，因此在用户获得访问百亿亿级设备的权限之前，必须开发适当的软件。该项目的研究人员是国际领先的专家，他们开发（启用新科学）和优化（使模拟更有效）最先进的材料软件，用于在HPC上运行模拟，他们来自国内外。我们开发的软件在学术界和工业界都有应用。目前，我们的社区消耗了英国高性能计算设施（ARCHER）的三分之一以上，大约有120,000个内核（峰值性能为2.5x10^15 Flop/s），我们预计不会有任何延迟，立即从ARCHER的继任者中获得最大的好处，当它在今年晚些时候向英国学术界可用时，它将由大约75万个内核（估计约为28x10^15 Flop/s）组成。百亿亿次计算机（按定义为10^18 Flop/s）将由更多的核心组成。然而，预计下一代国家计算机将不会提供从现有基础设施的平稳过渡，而是将经历英国国家设施的逐步变化，从传统的基于CPU的架构转变为托管（多个）多核加速器的CPU。在这些架构能够被充分利用之前，我们的许多软件包（如果不是全部的话）将需要进行重大更改。对软件进行适当的更改将减少核心之间的数据交换、管理CPU和加速器之间的通信，而且还将调整处理输入和输出数据的程序。根据呼吁的要求，我们将组建一个设计和开发工作组（DDWG），将研究软件工程师（rse）和数学和计算机科学专家与材料和分子建模（MMM）领域的广泛专家聚集在一起。我们代表了一个非常庞大和重要的社区，它已经建立了开发、资源管理和传播DDWG将利用的最佳实践的机制。为了最大限度地发挥英国对百亿亿次计算的可用资金的影响，我们确定了将使我们社区大多数人受益的解决方案。我们的DDWG旨在将问题的基础数学从实现的计算机科学中分离出来。我们将利用当前的最佳实践，以及在我们的领域和其他学科中正在开发的实践，特别是针对可以被许多材料软件调用的库，并提供通往异构体系结构的途径。在一个互补的发展中，我们将解决新的工作流程来管理和分析大量的模拟数据。我们将从定期会议和与其他发展工作小组的会议中获得宝贵的经验；以及与国内和国际项目合作伙伴的知识转移。承担初始工作并确定所需（指定为下一资助阶段的一部分的工作）将丰富我们的专业知识，并促进与材料软件开发商和海外百亿亿次计算机用户的国际合作。这项工作使英国MMM社区能够有效地利用百亿亿级高性能计算资源来解决EPSRC的许多重大挑战，包括功能材料的出现和纳米级设计（物理学）；拨号分子和定向组装扩展结构与目标性质（化学科学）；从原子到应用（工程）。

High Performance Computers (HPC), or supercomputers, offer exciting opportunities in understanding, developing and increasingly predicting the properties of complex materials through atomistic and electronic structure modelling; and the scope and power of our computational techniques continue to expand as the capability of the hardware grows. The advent of exascale systems is the next dramatic step in this evolution. There is a high cost of both purchasing and running such a system, so it is imperative that appropriate software is developed before users gain access to exascale facilities. The investigators of this project are internationally leading experts in developing (enabling new science) and optimising (making simulations more efficient) state-of-the-art materials software for running simulations on HPC, based here and abroad. Software that we have developed is used both in academia and in industry. Currently, our community consumes over a third of the UK's HPC facility (ARCHER) of approximately 120,000 cores (with a peak performance of 2.5x10^15 Flop/s) and we do not anticipate any delays in immediately getting the most out of the successor to ARCHER, which will be composed of approximately 750,000 cores (estimated at ~ 28x10^15 Flop/s) when it becomes available later this year to the UK academic community. Exascale computers (by definition >10^18 Flop/s) will be composed of many more cores. However, it is anticipated that the next generations of national computers will not provide a smooth transition from the existing infrastructures, but instead will undergo a step change for the UK national facilities, with a shift from conventional CPU based architectures to CPUs hosting (multiple) many-core accelerators. Many, if not all, of our software packages will require major changes before these architectures can be fully exploited. Appropriate changes to the software will effect a reduction in data exchange between cores, management of communications between CPU and accelerators, and, moreover, adaptation in our procedures for handling input and output data.As requested in the Call, we will form a design and development working group (DDWG) by bringing together Research Software Engineers (RSEs) and experts from mathematics and computer science with a wide range of domain experts in Materials and Molecular Modelling (MMM). We represent a very large and important community which has long established mechanisms for development, resource management, and disseminating best practices that the DDWG will exploit. To maximise the impact of the available UK funds for exascale computing, we identify solutions that will benefit most of our community.Our DDWG aims to separate out the fundamental mathematics of the problem from the computer science of implementation. We will exploit best current practices and those under development in our domain and across other disciplines in particular targeting libraries that can be called by many materials software and offer a route to heterogeneous architectures. In a complementary development, we will tackle new workflows to manage and analyse vast volumes of simulation data. We will gain valuable experience from our regular meetings and meetings with other DDWGs; and knowledge transfer with our national and international project partners. Undertaking of the initial work and identifying what is required (work earmarked as part of the next funding stage) will enrich our expertise and facilitate international collaborations with developers of materials software and users of overseas exascale computers.This work enables the UK MMM community to use exascale HPC resources efficiently to address many EPSRC Grand Challenges, including Emergence and Nanoscale Design of Functional Materials (Physics); Dial a Molecule and Directed Assembly of Extended Structures with Targeted Properties (Chemical Sciences); and Engineering From Atoms to Applications (Engineering).