Molecular dynamics integration time step dependence of the split integration symplectic method on system density

This paper shows that the maximal size of the integration time step of the Split Integration Symplectic Method (SISM) for molecular dynamics (MD) integration, a combination of the analytical solution of the high-frequency harmonic part of the Hamiltonian and the numerical solution of the low-frequency remaining part, depends on the system density. This approach was tested on a system of linear chain molecules. The numerical results indicate that the integration time step used by the SISM is limited by atoms' motion generated by the electrostatic and Lennard-Jones interactions in the system. As the density of the system increases, the size of the integration time step allowed by the SISM thus becomes smaller but remains significantly larger than possible by standard methods of the same order and complexity.