We present a computational steering approach for controlling, analyzing, and visualizing very large scale molecular dynamics simulations involving tens to hundreds of millions of atoms. Our approach relies on extensible scripting languages and an easy to use tool for building extensions and modules. The system is extremely easy to modify, works with existing C code, is memory efficient, and can be used from inexpensive workstations and networks. We demonstrate how we have used this system to manipulate data from production MD simulations involving as many as 104 million atoms running on the CM-5 and Cray T3D. We also show how this approach can be used to build systems that integrate common scripting languages (including Tcl/Tk, Perl, and Python), simulation code, user extensions, and commercial data analysis packages.

We present timings and performance numbers for a new short range three dimensional (3D) molecular dynamics (MD) code, SPaSM, on the Connection Machine-5 (CM-5).We demonstrate that rurM with more than 108 particles are now possible on massively parallel MIMD computers.To the best of our knowledge this ti at least an opder of magnitade more particles than what has previously been reported.Typical production runs show sustained performance (including communication) in the range of 47-50 GFlops on a 1024 node CM-5 with vector units (VUS).The speed of the code scales linearly with the number of processors and with the number of particles and shows 95% parallel eficiency in the speedup.Passing Multi-Cell Molecular Dynamics on the Connection Machine 5, Parall.Comp. (1993) (in press).