Supporting research communities with large-scale DFT in the next decade and beyond

今天，基于密度泛函理论(DFT)的第一性原理量子力学模拟与实验一起用于设计新材料。传统的DFT计算工作量随着原子数量的立方增加而增加，这限制了计算的实际规模。ONETEP是英国开发的世界领先的软件包，它使用线性缩放框架来实现更大规模的计算，与传统方法相比，独一无二的是不会损失精度。因此，ONETEP在构建和模拟更逼真的材质模型以及在多尺度模拟中包含它们的环境方面提供了无与伦比的能力。ONETEP从一开始就是为了利用超级计算机而开发的。由于其非平凡的公式和广泛的功能，它是一个由大约50万行代码组成的高度复杂的代码。ONETEP是一个学术社区代码，它来自CCP9，凝聚态物质的电子结构合作计算项目，将不同学科的学者聚集在一起，并形成了欧洲Psi-k网络的英国分支。2016年，ONETEP成为CCP9的旗舰项目，对英国学者免费。行业对ONETEP的暴露源于与Biovia的密切合作，Biovia实现了与他们的Material Studio用户界面的集成。这带来了相当大的商业影响和新的行业合作。在英国之外，ONETEP在爱尔兰和中国的开发者以及欧洲许多国家的用户以及美国、中国、墨西哥和南非的用户中越来越受欢迎。与所有软件一样，ONETEP需要不断发展和更新，才能保持领先地位。对于一个已经发展了20年的大型合作学术项目来说，这尤其具有挑战性。此外，一系列的发展，如激发态、电化学、嵌入和波函数方法，都需要广泛的改变。由于它们影响代码的核心算法，这些更改不可避免地导致了复杂性的增加。因此，代码现在需要采用新的结构，以确保其持续增长。与此同时，重要的是保持并进一步扩大用户和开发人员社区，以实现其主要目标，以满足科学界的需求。本项目旨在实现这两个相互关联的目标。它将重新设计整个代码，使内部结构合理化，以允许进一步开发并增强现有功能的互操作性。将始终遵循现代软件工程原则，与STFC SCD的计算物理和化学小组以及南安普顿、华威和帝国的研究软件工程师密切合作。与此同时，能够大规模计算晶体和半晶体材料的新功能的开发将满足许多研究人员在这一领域的需求，例如在CCP9和STFC设施的固态显微镜和光谱学社区。将开发工作流程工具并与ChemShell QM/MM代码相结合，以使生物分子模拟社区能够采用该代码。这些代码还将被移植到带有GPU加速器的新兴超级计算架构上。因此，该项目将支持固态材料和生物化学中部署基于DFT的第一原理量子模拟的快速扩展的社区。该项目将为新用户提供重要的沟通、参与以及专家培训和指导，以克服最初的访问障碍，并使他们能够使用代码在其不同的研究领域产生影响。针对代码用户和开发人员的培训活动将嵌入每个社区。

First-principles quantum-mechanical simulations based on density-functional theory (DFT), are today used hand in hand with experiment to design new materials. Conventional DFT has a computational effort which increases with the cube of the number of atoms and this limits the practical size of calculations. ONETEP is a world-leading UK-developed software package which uses a linear-scaling framework to enable calculations on much larger scales, uniquely without loss of accuracy compared to traditional methods. Thus ONETEP offers unmatched capabilities for constructing and simulating more realistic models of materials and including their environment in multiscale simulations.ONETEP has been developed from the beginning to take advantage of supercomputers. Due to its non-trivial formulation and wide-ranging functionality, it is a highly complex code consisting of around half a million lines of code.ONETEP is an academic community code which emerged from CCP9, the Collaborative Computational Project for the electronic structure of condensed matter, bringing together academics across disciplines, and forming the UK branch of the European Psi-k Network. In 2016 ONETEP became the flagship project of CCP9 and free to UK academics. Industrial exposure to ONETEP has resulted from close collaboration with BIOVIA, which has enabled integration with their Materials Studio user interface. This has led to considerable commercial impact and new industrial collaborations. Beyond the UK, ONETEP is gaining in popularity with developers in Ireland and China and users in many countries in Europe as well as the USA, China, Mexico and South Africa.As with all software, ONETEP needs to be continuously evolved and updated in order to stay at the cutting edge. This is particularly challenging for a large collaborative academic project that has evolved over two decades. Furthermore, a range of developments, such as excited states, electrochemistry, embedding and wavefunction methods, have required pervasive changes. Since they affect the core algorithms of the code, these changes have inevitably led to increased complexity. Thus the code now needs to adopt a new structure to ensure its continued growth. At the same time it is important to maintain and further widen the community of users and developers to fulfill its primary objective to cater for the needs of the scientific community.This project is targeted towards these two interconnected aims. It will re-engineer the code in its entirety, rationalising internal structure to allow further development and enhance the interoperability of existing functionality. Modern software engineering principles will be followed throughout, in close collaboration with the computational physics and chemistry groups of STFC SCD and research software engineers in Southampton, Warwick and Imperial. At the same time developments of new functionality to enable large-scale calculations of crystalline and semicrystalline materials will satisfy a demand in this area by many researchers, such as in the CCP9 and the solid state microscopy and spectroscopy communities at STFC Facilities. Workflow tools and coupling with the ChemShell QM/MM code will be developed to allow adoption of the code by the biomolecular simulations community. The code will also be ported to emerging supercomputing architectures with GPU accelerators. Thus the project will support the rapidly-expanding communities within solid-state materials and biochemistry that deploy first-principles quantum simulations based on DFT. The project will deliver significant communication, engagement, and expert training and mentoring of new users to overcome initial barriers to access and enable them to use the code to make impact in their diverse research areas. Training events for both users and developers of the code will be embedded within each community.