Extending molecular simulation time scales: Parallel in time integrations for highlevel quantum chemistry and complex force representations
Parallel in time simulation algorithms are presented and applied to conventional molecular dynamics (MD) and ab initio molecular dynamics (AIMD) models of realistic complexity. Assuming that a forward time integrator, f (e.g., Verlet algorithm), is available to propagate the system from time t{sub i} (trajectory positions and velocities x{sub i} = (r{sub i}, v{sub i})) to time t{sub i+1} (x{sub i+1}) by x{sub i+1} = f{sub i}(x{sub i}), the dynamics problem spanning an interval from t{sub 0}…t{sub M} can be transformed into a root finding problem, F(X) = [x{sub i} − f(x{sub (i−1})]{sub i} {sub =1,M} = 0, for the trajectory variables. The root finding problem is solved using a variety of root finding techniques, including quasiNewton and preconditioned quasiNewton schemes that are all unconditionally convergent. The algorithms are parallelized by assigning a processor to each timestep entry in the columns of F(X). The relation of this approach to other recently proposed parallel in time methods is discussed, and the effectiveness of various approaches to solving the root finding problem is tested. We demonstrate that more efficient dynamical models based on simplified interactions or coarsening timesteps provide preconditioners for the root finding problem. However, for MD and AIMD simulations, suchmore »
 Authors:

^{[1]};
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 Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352 (United States)
 Department of Mathematics, University of Chicago, Chicago, Illinois 60637 (United States)
 Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093 (United States)
 Publication Date:
 OSTI Identifier:
 22303583
 Resource Type:
 Journal Article
 Resource Relation:
 Journal Name: Journal of Chemical Physics; Journal Volume: 139; Journal Issue: 7; Other Information: (c) 2013 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; 97 MATHEMATICAL METHODS AND COMPUTING; ALGORITHMS; CONTROL; ELECTRONIC STRUCTURE; HYDROCHLORIC ACID; INTERACTIONS; MOLECULAR DYNAMICS METHOD; SIMULATION