Knowing the rate at which particle radiation releases energy in a material,the“stopping power,”is key to designing nuclear reactors,medical treatments,semiconductor and quantum materials,and many other technologies....Knowing the rate at which particle radiation releases energy in a material,the“stopping power,”is key to designing nuclear reactors,medical treatments,semiconductor and quantum materials,and many other technologies.While the nuclear contribution to stopping power,i.e.,elastic scattering between atoms,is well understood in the literature,the route for gathering data on the electronic contribution has for decades remained costly and reliant on many simplifying assumptions,including that materials are isotropic.We establish a method that combines time-dependent density functional theory(TDDFT)and machine learning to reduce the time to assess new materials to hours on a supercomputer and provide valuable data on how atomic details influence electronic stopping.Our approach uses TDDFT to compute the electronic stopping from first principles in several directions and then machine learning to interpolate to other directions at a cost of 10 million times fewer core-hours.We demonstrate the combined approach in a study of proton irradiation in aluminum and employ it to predict how the depth of maximum energy deposition,the“Bragg Peak,”varies depending on the incident angle—a quantity otherwise inaccessible to modelers and far outside the scales of quantum mechanical simulations.The lack of any experimental information requirement makes our method applicable to most materials,and its speed makes it a prime candidate for enabling quantum-to-continuum models of radiation damage.The prospect of reusing valuable TDDFT data for training the model makes our approach appealing for applications in the age of materials data science.展开更多
The Globus Toolkit （GT） has been developed since the late 1990s to support the development of serviceoriented distributed computing applications and infrastructures. Core GT components address, within a common frame...The Globus Toolkit （GT） has been developed since the late 1990s to support the development of serviceoriented distributed computing applications and infrastructures. Core GT components address, within a common framework, fundamental issues relating to security, resource access, resource management, data movement, resource discovery, and so forth. These components enable a broader ＂Globus ecosystem＂ of tools and components that build on, or interoperate with, GT functionality to provide a wide range of useful application-level functions. These tools have in turn been used to develop a wide range of both ＂Grid＂ infrastructures and distributed applications. I summarize here the principal characteristics of the recent Web Services-based GT4 release, which provides significant improvements over previous releases in terms of robustness, performance,, usability, documentation, standards compliance, and functionality. I also introduce the new ＂dev.globus＂ community development process, which allows a larger community to contribute to the development of Globus software.展开更多
The Ediacaran Period(~635–539 Ma)was a critical time in Earth history due to large increases in atmospheric and oceanic oxygen levels and rapid evolution of early animals[1].It was also an interval of major climatic ...The Ediacaran Period(~635–539 Ma)was a critical time in Earth history due to large increases in atmospheric and oceanic oxygen levels and rapid evolution of early animals[1].It was also an interval of major climatic and geochemical perturbations,such as the~580-Ma Gaskiers Glaciation[2](Fig.S1 online)and the late Ediacaran Shuram Excursion(SE;also known as DOUNCE or EN3 in South China,see Fig.S2 online),which was the largest negative carbonate carbon isotope(δ13Ccarb)excursion in Earth history[3,4].In contrast to established redox,biological,and C-cycling records for the Ediacaran,however,no secular,high-resolution paleotemperature record with climatic significance has been reported to date,impeding our understanding of the relationships among major environmental,biological,geochemical,and climatic processes and milestones.展开更多
基金supported in part by the U.S.Department of Energy under contract DE-AC02-06CH11357,and used resources of the Argonne Leadership Computing Facility,a DOE Office of Science User Facility supported under Contract DE-AC02-06CH11357funding by the Office of Naval Research(Grant No.N00014-18-1-2605)the National Science Foundation(Grant Nos.OAC-1740219 and OAC-2209857).
文摘Knowing the rate at which particle radiation releases energy in a material,the“stopping power,”is key to designing nuclear reactors,medical treatments,semiconductor and quantum materials,and many other technologies.While the nuclear contribution to stopping power,i.e.,elastic scattering between atoms,is well understood in the literature,the route for gathering data on the electronic contribution has for decades remained costly and reliant on many simplifying assumptions,including that materials are isotropic.We establish a method that combines time-dependent density functional theory(TDDFT)and machine learning to reduce the time to assess new materials to hours on a supercomputer and provide valuable data on how atomic details influence electronic stopping.Our approach uses TDDFT to compute the electronic stopping from first principles in several directions and then machine learning to interpolate to other directions at a cost of 10 million times fewer core-hours.We demonstrate the combined approach in a study of proton irradiation in aluminum and employ it to predict how the depth of maximum energy deposition,the“Bragg Peak,”varies depending on the incident angle—a quantity otherwise inaccessible to modelers and far outside the scales of quantum mechanical simulations.The lack of any experimental information requirement makes our method applicable to most materials,and its speed makes it a prime candidate for enabling quantum-to-continuum models of radiation damage.The prospect of reusing valuable TDDFT data for training the model makes our approach appealing for applications in the age of materials data science.
基金Work on Giobus has been supported in part by the Mathematical, Information, and Computational Sciences Division subprogram of the 0ffice of Advanced Scientific Computing Research, U.S. Department of Energy, under Contract W-31-109-Eng-38, by the National Science Foundation （NSF）＇s 0ffice of Cyberinfrastructure and other programs, and by IBM, DARPA, NASA, Microsoft, the UK Engineering and Physical Sciences Research Council and Department of Trade and Industry, and the Swedish Research Council. I report here on the work of many talented colleagues, as detailed at www.globus.org. The core team is currently based primarily at Argonne National Lab, U. Chicago, the USC Information Sciences Institute, U. Edinburgh, the Royal Institute of Technology, the National Center for Supercomputing Applications, and Univa Corporation, but many others have also contributed to Globus code, documentation, and testing, and/or made our work worthwhile by using the software.
文摘The Globus Toolkit （GT） has been developed since the late 1990s to support the development of serviceoriented distributed computing applications and infrastructures. Core GT components address, within a common framework, fundamental issues relating to security, resource access, resource management, data movement, resource discovery, and so forth. These components enable a broader ＂Globus ecosystem＂ of tools and components that build on, or interoperate with, GT functionality to provide a wide range of useful application-level functions. These tools have in turn been used to develop a wide range of both ＂Grid＂ infrastructures and distributed applications. I summarize here the principal characteristics of the recent Web Services-based GT4 release, which provides significant improvements over previous releases in terms of robustness, performance,, usability, documentation, standards compliance, and functionality. I also introduce the new ＂dev.globus＂ community development process, which allows a larger community to contribute to the development of Globus software.
基金supported by the National Natural Science Foundation of China(41825019,42130208,41821001,and 42102343)the Programme of Introducing Talents of Discipline to Universities(BP0820004)+1 种基金China Postdoctoral Science Foundation(2020M682515)an award from “Laboratoire Excellence”LabexMER(ANR-10-LABX-19)。
文摘The Ediacaran Period(~635–539 Ma)was a critical time in Earth history due to large increases in atmospheric and oceanic oxygen levels and rapid evolution of early animals[1].It was also an interval of major climatic and geochemical perturbations,such as the~580-Ma Gaskiers Glaciation[2](Fig.S1 online)and the late Ediacaran Shuram Excursion(SE;also known as DOUNCE or EN3 in South China,see Fig.S2 online),which was the largest negative carbonate carbon isotope(δ13Ccarb)excursion in Earth history[3,4].In contrast to established redox,biological,and C-cycling records for the Ediacaran,however,no secular,high-resolution paleotemperature record with climatic significance has been reported to date,impeding our understanding of the relationships among major environmental,biological,geochemical,and climatic processes and milestones.
