Materials by Design G.E. Ice and T. Ozaki Park Vista Hotel Gatlinburg, Tennessee September 5-6, 2014

Materials Materials Central to All Energy Technologies Photovoltaics Lightweight materials Energy Storage Fuel Cells Nuclear Fossil Grid Wind Geothermal

Exciting to hear of areas of mutual interest Grateful for the chance to share ideas with our colleagues from Japan Numerous areas of common interest Think big!

Breakout Charge Questions, continued 1.What technical breakthroughs in science and engineering research can be enabled by exascale platforms and are attractive targets for Japan-US collaboration over the next 10 years? –Please prioritize discussions around opportunities for collaborative Japan-US R&D relationships. Materials with inhomogeneities (e.g. interfaces, defects and multiphase materials) - where size is needed Higher accuracy methods Finite temperature calculations

Breakout Charge Questions, continued 2.What is the representative suite of applications in your research area, available today, which should form the basis of your co- design communication with computer architects? DFT, QMC, MD, Atomistic KMC, Phase Field a)How are these applications currently constrained by compute and data resources, programming models, or available software tools? Lack of spline evaluation for QMC, spherical harmonics, etc. a)What are the gaps in available applications and application workflows, and requirements to fill these gaps? Need for efficient scalable methods, optimized libraries, systematic way to validate competitive codes for speed and accuracy a)Which of these are ripe for collaboration within the context of Japan-US cooperation? All of the above

Breakout Charge Questions, continued 3.How can the application research community, represented by a topical breakout at this workshop, constructively engage the vendor community in co- design? a)How should these various aspects of the application and architecture be optimized for effective utilization of exascale compute and data resources? b)Consider all aspects of exascale application: formulation and basic algorithms, programming models & environments, data analysis and management, hardware characteristics. Identify and develop mini apps

4.How can you best manage the “conversations” with computer designers/architects around co-design such that (1) they are practical for computer design, and (2) the results are correctly interpreted within both communities? a)What are the useful performance benchmarks from the perspective of your domain? Time to solution, accuracy, robustness a)Are mini-apps an appropriate and/or feasible approach to capture your needs for communication to the computer designers? Yes a)Are there examples of important full applications that are an essential basis for communication with computer designers? b)Can these be simplified into skeleton apps or mini-apps to simplify and streamline the co-design conversation Scientists have identified rate limiting steps- can possibly use these as a model

Breakout Charge Questions, continued 5.Describe the most important programming models and environment in use today within your community and characterize these as sustainable or unsustainable. a)Do you have appropriate methods and models to expose application parallelism in a high-performance, portable manner? No- but we used to have it. a)Are best practices in software engineering often or seldom applied? Seldom a)Going forward, what are the critically important programming languages? Fortran, C++, python, C a)On which libraries and/or domain-specific languages (DSL) is your research community dependent? BLAS, LAPACK, FFT a)Are new libraries or DSL’s needed in your research domain? Yes a)Are these aspects of your programming environment sustainable or are new models needed to ensure their availability into the future? ?

Breakout Charge Questions, continued 6.Does your community have mature workflow tools that are implemented within leadership computing environments to assist with program composition, execution, analysis, and archival of results? If no, what are your needs and is their opportunity for value added? No! a)For example, do you need support for real-time, interactive workflows to enable integration with real-time data flows?

Breakout Charge Questions, continued 7.What are the new programming models, environments and tools that need to be developed to achieve our science goals with sustainable application software? Architectural and performance portability Fault resilient software Code accessible to non-specialists/ novices Maintainable framework for Japan/U.S. software

Breakout Charge Questions, continued 8.Is there a history, a track record in your research community for co-design for HPC systems in the installed machines in the past, and is there any co-design study done for these systems to document the effectiveness of co- design? No

How shall we build sustainable, multidisciplinary teams and research collaborations, including vendor partners, necessary to achieve our workshop goals? Defined objective- scalable materials computation, e.g. order n scaling for DFT, QMC and Wang Landau Collaborative funding for materials software development and support which prepares for exascale What are the appropriate collaborative agreements and organization to enable Japan and the US collaborate on exascale science application development in a mutually beneficial way? Annex to high level MOUs to include materials software developments How are we going to maintain these collaborations over time? Exchange of postdoctoral students Joint software development and maintenance Exchange of computer time