<i>SIR2004</i>: an improved tool for crystal structure determination and refinement

SIR2004 is the evolution of the SIR2002 program [Burla, Camalli, Carrozzini, Cascarano, Giacovazzo, Polidori &amp; Spagna (2003). J. Appl. Cryst. 36 , 1103]. It is devoted to the solution of crystal structures by direct and Patterson methods. Several new features implemented in SIR2004 make this program efficient: it is able to solve ab initio both small/medium-size structures as well as macromolecules (up to 2000 atoms in the asymmetric unit). In favourable circumstances, the program is also able to solve protein structures with data resolution up to 1.4–1.5 Å, and to provide interpretable electron density maps. A powerful user-friendly graphical interface is provided.