Crystal structure solution of small-to-medium-sized molecules at non-atomic resolution

Data resolution limits the information carried by diffraction data and is
therefore the most critical limit for the success of ab initio crystal structure
solution. To overcome this limit, two methods have recently been proposed,
namely the correction of resolution bias in electron-density maps and
extrapolation of the structure factors beyond the data resolution limit. The
first method has successfully been applied to powder data and the second to
protein data. Neither of them has been applied to single-crystal data from small
or medium-sized molecules. A third technique, the active use of the PSI-0
triplets in a tangent procedure, was applied to small molecules in the early days
of crystallography, but it soon became obsolete because of the great success of
methods combining reciprocal and direct space techniques. This paper explores
the role of data resolution for small-to-medium-sized molecules and studies the
usefulness of three auxiliary techniques, i.e. active use of the PSI-0 triplets,
resolution bias correction and extrapolation of the structure factors