  To determine crystal structures from an X-ray diffraction (XRD) pattern
containing multiple unknown phases, a data-assimilated crystal growth (DACG)
simulation method has been developed. The XRD penalty function selectively
stabilizes the structures in the experimental data, promoting their grain
growth during simulated annealing. Since the XRD pattern is calculated as the
Fourier transform of the pair distribution function, the DACG simulation can be
performed without prior determination of the lattice parameters. We applied it
to C (graphite and diamond) and SiO$_2$ (low-quartz and low-cristobalite)
systems, demonstrating that the DACG simulation successfully reproduced
multiple crystal structures.
