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Per-Åke Malmqvist

Senior lecturer

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Parallelization of a multiconfigurational perturbation theory

Author

  • Steven Vancoillie
  • Mickael G. Delcey
  • Roland Lindh
  • Victor Vysotskiy
  • Per-Åke Malmqvist
  • Valera Veryazov

Summary, in English

In this work, we present a parallel approach to complete and restricted active space second-order perturbation theory, (CASPT2/RASPT2). We also make an assessment of the performance characteristics of its particular implementation in the Molcas quantum chemistry programming package. Parallel scaling is limited by memory and I/O bandwidth instead of available cores. Significant time savings for calculations on large and complex systems can be achieved by increasing the number of processes on a single machine, as long as memory bandwidth allows, or by using multiple nodes with a fast, low-latency interconnect. We found that parallel efficiency drops below 50% when using 8-16 cores on the shared-memory architecture, or 16-32 nodes on the distributed-memory architecture, depending on the calculation. This limits the scalability of the implementation to a moderate amount of processes. Nonetheless, calculations that took more than 3 days on a serial machine could be performed in less than 5 h on an InfiniBand cluster, where the individual nodes were not even capable of running the calculation because of memory and I/O requirements. This ensures the continuing study of larger molecular systems by means of CASPT2/RASPT2 through the use of the aggregated computational resources offered by distributed computing systems. (c) 2013 Wiley Periodicals, Inc.

Department/s

  • Computational Chemistry
  • eSSENCE: The e-Science Collaboration

Publishing year

2013

Language

English

Pages

1937-1948

Publication/Series

Journal of Computational Chemistry

Volume

34

Issue

22

Document type

Journal article

Publisher

John Wiley & Sons Inc.

Topic

  • Theoretical Chemistry (including Computational Chemistry)

Keywords

  • parallellization
  • CASPT2
  • multiconfigurational perturbation theory
  • high
  • performance computing

Status

Published

ISBN/ISSN/Other

  • ISSN: 1096-987X