National Institute of Chemistry
Hajdrihova 19, 1001 Ljubljana, Slovenia
E-Mail: dusa@kihp5.ki.si
A new Split Integration Symplectic Method (SISM) for molecular dynamics (MD) simulations is described. The method is based on splitting of the total Hamiltonian of the system into the harmonic part and the remaining part in such a way that both parts can be efficiently computed. The Hamilton equations of motion are then solved using the second order generalized leap-frog integration scheme in which the high-frequency motions are treated analytically by the normal mode analysis which is carried out only onece, at the beginning of the calculation. The proposed algorithm requires only one force evaluation per integration step, the computation cost per integration step is modestly larger as that of the standard leap-frog-Verlet method, and it allows an integration time step up to an order of magnitude larger than can be used by other methods of the same order. This should significantly extend the scope of the presently used algorithms and thus contribute to the general applicability of molecular dynamics algorithms.