Efficient algorithms for rigid body integration using optimized splitting methods and exact free rotational motion

Abstract

Hamiltonian splitting methods are an established technique to derive stable and accurate integration schemes in molecular dynamics, in which additional accuracy can be gained using force gradients. For rigid bodies, a tradition exists in the literature to further split up the kinetic part of the Hamiltonian, which lowers the accuracy. The goal of this note is to comment on the best combination of optimized splitting and gradient methods that avoids splitting the kinetic energy. These schemes are generally applicable, but the optimal scheme depends on the desired level of accuracy. For simulations of liquid water it is found that the velocity Verlet scheme is only optimal for crude simulations with accuracies larger than 1.5%, while surprisingly a modified Verlet scheme (HOA) is optimal up to accuracies of 0.4% and a fourth order gradient scheme (GIER4) is optimal for even higher accuracies.

2 pages, 1 figure. Added clarifying comments. Accepted for publication in the Journal of Chemical Physics

References in corpus (2)

• Numerical implementation of the exact dynamics of free rigid bodies
• Symplectic algorithms for simulations of rigid body systems using the exact solution of free motion

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