The principal investigator studies and develops computational methods suitable for parallel and vector computers to solve molecular dynamics problems. He emphasizes time-stepping techniques to compute motion in many-body interactions, studies the importance of symplectic methods, and investigates strategies for taking larger time steps. To test the ideas, the principal investigator implements them in a software package for modeling macromolecules. The many-body problem-how a set of distinct objects move under the influence of forces that change as the objects move-is classical and hard. For instance, the motion of planets in the solar system can be thought of as a 10 body problem where the primary force is gravity. The motion of molecules is particularly difficult because such problems involve so many objects and the nature of the forces is so complicated. The problems arise in areas of material science, structural biology, and design of drugs. This work aims to develop software and algorithms to solve such problems rapidly on computers.