Ab initio structure determinations by direct-space methods: tests of low-density elimination

The low‐density elimination method, which was developed for phase extension and refinement, has been investigated regarding its power to solve crystal structures starting from completely random phase sets. The method employs a multi‐solution strategy. Low‐symmetry structures are easily solvable where phase restrictions are only applied to a few reflections. Even with high‐symmetry structures, a reasonable solution was obtained regarding centric reflections as general reflections. It is also shown that the structure of a small protein ribonuclease Ap1 is solvable if the positions of the five S atoms in the protein are known.