New methods for incorporating nonholonomic constraints into molecular dynamics simulations

Three new algorithms are presented for incorporating nonholonomic constrain ts into molecular dynamics (MD) simulations, along with any additional holo nomic constraints. The advantages of these algorithms over the commonly use d Gaussian approach are discussed. Of the three algorithms presented, the o ptimal one can efficiently ensure satisfaction of large numbers of nonholon omic and holonomic constraints at every MD time step, without introducing a dditional numerical errors in the coordinate or velocity trajectories. Nume rical results from MD simulations of Lennard-Jones particles, rigid water m olecules, and partially rigid methane molecules are given, illustrating the advantages of this algorithm. In addition, this algorithm is suggested as a more advantageous alternative to velocity scaling, for maintaining fixed temperature during equilibration of constant energy MD simulations. (C) 199 9 American Institute of Physics. [S0021-9606(99)50828-3].