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An Isaac Newton Institute Workshop

Effective Computational Methods for Highly Oscillatory Problems: The Interplay between Mathematical Theory and Applications

Treatment of Oscillations in Classical Molecular Dynamics

Author: Robert D. Skeel (Purdue University)


Atomic oscillations present in classical molecular dynamics (MD) restrict the step size that can be used. These oscillations are decidedly nonlinear, and there is only a modest separation of temporal scales. For reasons to be explained, amplitudes of the highest frequency oscillations are small, and, hence, MD is an example of a (mildly) stiff oscillatory problem. Actually, getting accurate trajectories is not usually the aim of MD; instead, time averages or time correlation functions are sought, and the implications of this are examined. Two techniques for lengthening the step size have found general use: multiple time stepping and bond-length constraints. Accuracy and stability of these techniques is discussed.

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