A special-purpose computer for molecular dynamics: GRAPE-2A.

Molecular dynamics simulations have been extensively used in research of proteins. Since these simulations are quite computer intensive, their acceleration is of main interest of the research. In molecular dynamics simulations, almost all computing time is consumed in calculating the forces between particles, e.g., Coulomb and van der Waals forces. We have designed and built GRAPE-2A (GRAvity PipE 2A), a special-purpose computer for use in simulations of classical many-body systems. GRAPE-2A calculates forces exerted on a particle from the other particles. GRAPE-2A can calculate force of an arbitrary functional form of a central force. The host computer, which is connected to GRAPE-2A through the VME bus, performs other calculations such as time integration. The peak speed of GRAPE-2A is 180 Mflops. We can also stimulate systems with periodic boundary conditions by the Ewald method, using GRAPE-2A and another special-purpose computer, WINE (Wave space INtegrator for the Ewald method).