Parallelization of a multiconfigurational perturbation theory

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title = "Parallelization of a multiconfigurational perturbation theory",
abstract = "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.",
keywords = "parallellization, CASPT2, multiconfigurational perturbation theory, high, performance computing",
author = "Steven Vancoillie and Delcey, {Mickael G.} and Roland Lindh and Victor Vysotskiy and Per-{\AA}ke Malmqvist and Valera Veryazov",
note = "The information about affiliations in this record was updated in December 2015. The record was previously connected to the following departments: Theoretical Chemistry (S) (011001039)",
year = "2013",
doi = "10.1002/jcc.23342",
language = "English",
volume = "34",
pages = "1937--1948",
journal = "Journal of Computational Chemistry",
issn = "1096-987X",
publisher = "John Wiley and Sons",
number = "22",