A divideconquerrecombine algorithmic paradigm for large spatiotemporal quantum molecular dynamics simulations
We introduce an extension of the divideandconquer (DC) algorithmic paradigm called divideconquerrecombine (DCR) to perform large quantum molecular dynamics (QMD) simulations on massively parallel supercomputers, in which interatomic forces are computed quantum mechanically in the framework of density functional theory (DFT). In DCR, the DC phase constructs globally informed, overlapping localdomain solutions, which in the recombine phase are synthesized into a global solution encompassing large spatiotemporal scales. For the DC phase, we design a lean divideandconquer (LDC) DFT algorithm, which significantly reduces the prefactor of the O(N) computational cost for N electrons by applying a densityadaptive boundary condition at the peripheries of the DC domains. Our globally scalable and locally efficient solver is based on a hybrid realreciprocal space approach that combines: (1) a highly scalable realspace multigrid to represent the global charge density; and (2) a numerically efficient planewave basis for local electronic wave functions and charge density within each domain. Hybrid spaceband decomposition is used to implement the LDCDFT algorithm on parallel computers. A benchmark test on an IBM Blue Gene/Q computer exhibits an isogranular parallel efficiency of 0.984 on 786 432 cores for a 50.3 × 10{sup 6}atom SiC system. As a test of production runs, LDCDFTbased QMDmore »
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 Collaboratory for Advanced Computing and Simulations, Department of Physics and Astronomy, Department of Computer Science, and Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 900890242 (United States)
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 Publication Date:
 OSTI Identifier:
 22253376
 Resource Type:
 Journal Article
 Resource Relation:
 Journal Name: Journal of Chemical Physics; Journal Volume: 140; Journal Issue: 18; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ALLOYS; CHARGE DENSITY; DECOMPOSITION; DENSITY; DENSITY FUNCTIONAL METHOD; EFFICIENCY; EXCITED STATES; HYBRIDIZATION; INTERATOMIC FORCES; MOLECULAR DYNAMICS METHOD; MONTE CARLO METHOD; SILICON CARBIDES; SIMULATION; SOLIDS; TIME DEPENDENCE; WAVE FUNCTIONS