A software system for rigid-body modelling of solution scattering data

A computer system for rigid body modelling against solution scattering data is described. Fast algorithms to compute scattering from a complex of two arbitrary positioned subunits are implemented and coupled with the graphics program ASSA (Kozin, Volkov & Svergun, 1997, J. Appl. Cryst. 30, 811-815). Mutual positions and orientations of the subunits (represented by low-reso lution envelopes or by atomic models) can be determined by interactively fi tting the experimental scattering curve from the complex. The system runs o n the major Unix platforms (SUN, SGI and DEC workstations).