Limits on phonon information extracted from neutron pair-density functions

TL;DR

This paper investigates the extent to which neutron pair-density functions can reveal lattice dynamics, concluding that while generally limited, they can accurately determine phonon properties in simple monatomic metals.

Contribution

The study clarifies the limitations of PDF analysis for complex systems and demonstrates its potential for accurately extracting phonon information in simple monatomic metals.

Findings

PDF alone cannot accurately construct phonon dispersions in complex systems.

For simple monatomic metals, phonon frequencies can be obtained within a few percent accuracy.

The results challenge previous claims about the sufficiency of PDF for detailed phonon analysis.

Abstract

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 Roeder [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.