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-resolution envelopes or by atomic models) can be determined by interactively fitting the experimental scattering curve from the complex. The system runs on the major Unix platforms (SUN, SGI and DEC workstations).