The second example illustrates the behaviour of the method with respect to
missing data. This example was constructed as follows : one-dimensional data
were calculated from a hypothetical (1D) structure containing two Gaussians
in the asymmetric unit of the m cell (where
denotes the
one-dimensional lattice). This hypothetical structure is shown
on the far left panel in the figure below, and the data calculated by
Fourier transforming this structure only included 18 strong reflections.
The middle column of graphs
shows the conventional and GraphEnt syntheses that were obtained when all these
18 reflections were included in the calculation (and, of course, both are
essentially identical with the starting structure). When the calculation was
repeated with 6 reflections missing from the data set, the conventional map
(top, right-hand corner graph) was far from ideal : a new peak appears at
x = 0.5, and the relative heights of the two Gaussians are no longer the
same. In sharp contrast, the GraphEnt map (lower, right-hand side graph) is
almost identical with the synthesis calculated with all data (and with the
correct structure).