SnB version 2.2: an example of crystallographic multiprocessing

The computer program SnB implements a direct-methods algorithm, known as Shake-and-Bake, which optimizes trial structures consisting of randomly positioned atoms. Although large Shake-and-Bake applications require signi®cant amounts of computing time, the algorithm can be easily implemented in parallel in order to decrease the real time required to achieve a solution. By using a master±worker model, SnB version 2.2 is amenable to all of the prevalent modern parallel-computing platforms, including (i) shared-memory multiprocessor machines, such as the SGI Origin2000, (ii) distributed-memory multiprocessor machines, such as the IBM SP, and (iii) collections of workstations, including Beowulf clusters. A linear speedup in the processing of a ®xed number of trial structures can be obtained on each of these platforms.