Collaborative Research: SI2-SSI: Removing Bottlenecks in High Performance Computational Science

计算化学已在科学和工程领域变得无处不在。计算化学代码的众多用途包括帮助设计具有特定性质的新材料、了解与人体相关的蛋白质折叠动力学、了解生产生物燃料的酶催化机制以及识别和表征大气中的气态物质。由于计算化学模拟可能需要大量的计算机、内存和磁盘空间，因此这项研究的重点之一是通过开发能够有效地将大分子分割成更小的碎片的方法来减少对计算机资源的需求，同时利用具有数千个计算机核心的计算机。主要研究人员是多个计算化学程序的开发人员，每个程序都具有独特的功能，需要花费数年的时间来开发和实施。为了最大限度地减少进一步的开发工作并最大限度地利用独特功能，本研究的第二个重点是开发每个程序访问其他程序的独特功能和数据的能力。构建具有越来越多计算核心的高性能计算机的一个主要瓶颈是驱动此类系统所需的功率。研究团队解决功耗问题的一种方法是探索低功耗架构的实用性，例如用于计算化学计算的图形处理单元。所有新开发的代码都将通过网络免费提供给用户社区。该项目提出了一种集成的计算科学方法，用于非常高质量的电子结构和动力学计算，该方法将（a）可供开发和应用社区广泛使用，（b）有能力解决人们非常感兴趣的问题，例如液体和溶剂效应的特性，以及高精度的光化学/光生物动力学，（c）在可预见的未来提供互操作性和可持续性，以及（d）解决包括功耗在内的瓶颈加速器。主要目标是向广大社区提供易于使用的新的、准确的方法，并为进一步的代码改进和开发提供清晰的路径。作为拟议工作的一部分，除了通常的期刊文章和公开演讲之外，研究人员还将在重要的全国会议上组织研讨会，以便尽可能广泛的用户群体能够使用所开发的专业知识和软件。 所有开发的代码都可以在网络上轻松下载。拟议的研究将开发新的互操作性范式，重点关注广受欢迎的程序套件 GAMESS、NWChem、PSI4 和 AIMS 动力学代码。还包括基于云的客户端-服务器模型、通用量子化学驱动程序和新颖的数据管理方法。代码的集成将通过利用 PI 开发计算科学中的可互操作方法和数据接口的综合专业知识来完成。此外，还将开发几种新方法，包括新颖的显式（R12）相关方法，这些方法将与最准确的理论水平相结合：多参考和最准确和新颖的耦合聚类方法，以及解析导数的推导和实现。通过利用几乎完美扩展到千万亿级的新型破碎方法，大分子系统的适用性将变得可行。

Computational chemistry has become ubiquitous throughout the fields of science and engineering. Among the many uses of computational chemistry codes are to aid in the design of new materials with specific properties, to understand protein folding dynamics related to the human body, to understand the mechanisms of enzyme catalysis to produce biofuels, and to identify and characterize gaseous species in the atmosphere. Because computational chemistry simulations can require large amounts of computer, memory and disk space, one focus of this research is to reduce the demands on computer resources by exploiting methods that can efficiently fragment large molecules into smaller pieces and at the same time take advantage of computers that have many thousands of computer cores. The principal investigators are developers of several computational chemistry programs, each of which has unique functionalities that have taken multiple person-years to develop and implement. In order to minimize further development efforts and to maximize the utility of the unique features, a second key focus of this research will be to develop the ability of each program to access the unique features and data of the other programs. A major bottleneck in the effort to construct high performance computers with more and more compute cores is the power that is required to drive such systems. One way that the research team will address the power issue is to explore the utility of low power architectures, such as graphical processing units for computational chemistry calculations. All of the newly developed codes will be made available to the user community by web download at no cost.This project presents an integrated computational science approach to very high quality electronic structure and dynamics calculations that will (a) be broadly accessible to both the development and applications communities, (b) have the capability to address problems of great interest, such as the properties of liquids and solvent effects, and photochemical/photobiological dynamics with high accuracy, (c) provide interoperability and sustainability into the foreseeable future, and (d) solve bottlenecks including power consumption using accelerators. A primary goal is to provide to the broad community new, accurate approaches that may be easily used, with a clear path forward to further code improvement and development. As part of the proposed effort, in addition to the usual outlets of journal articles and public presentations, the investigators will organize workshops at prominent national meetings, so that the expertise and software developed will be available to as broad a group of users as possible. All of the developed codes will be available on the web for easy downloads. The proposed research will develop new paradigms for interoperability, with a focus on the highly popular program suites GAMESS, NWChem, PSI4 and the AIMS dynamics code. Also included will be a cloud-based client-server model, a common quantum chemistry driver and novel data management approaches. The integration of the codes will be accomplished by making use of the combined expertise of the PIs in developing interoperable methods and data interfaces in computational science. In addition, several new methods will be developed, including novel explicit (R12) correlation methods that will be integrated with the most accurate levels of theory: multi-reference and the most accurate and novel coupled cluster methods, as well as the derivation and implementation of analytic derivatives. Applicability to large molecular systems will be made feasible by drawing upon novel fragmentation methods that scale nearly perfectly to the petascale.