  The paper describes an extension of the Liga algorithm for structure solution
from atomic pair distribution function (PDF), to handle periodic crystal
structures with multiple elements in the unit cell. The procedure is performed
in 2 separate steps - at first the Liga algorithm is used to find unit cell
sites consistent with pair distances extracted from the experimental PDF. In
the second step the assignment of atom species over cell sites is solved by
minimizing the overlap of their empirical atomic radii. The procedure has been
demonstrated on synchrotron x-ray PDF data from 16 test samples. The structure
solution was successful for 14 samples including cases with enlarged super
cells. The algorithm success rate and the reasons for failed cases are
discussed together with enhancements that should improve its convergence and
usability.
