Limits on phonon information extracted from neutron pair-density functions

We explore the possibility of extracting information about lattice dynamics in simple crystal structures from the neutron pair-density function (PDF) through inverse data analysis. Contrary to the claims by Dimitrov, Louca, and Roder [Phys. Rev. B 60, 6204 (1999)], and in agreement with recent work by Reichardt and Pintschovius [Phys. Rev. B 63, 174302 (2001)], we find that the PDF alone is not sufficient for constructing accurate phonon dispersions in the entire Brillouin zone in systems with complex lattice dynamics. However, our numerical simulations show that for monatomic fcc and bcc crystal structures it is, in principle, possible to obtain phonon moments of complex metals as well as phonon frequencies of simple metals within a few percent accuracy.