title: Direct assignment of molecular vibrations via normal mode analysis of the neutron dynamic pair distribution function technique.
abstract: For over a century, vibrational spectroscopy has enhanced the study of materials. Yet, assignment of particular molecular motions to vibrational excitations has relied on indirect methods. Here, we demonstrate that applying group theoretical methods to the dynamic pair distribution function analysis of neutron scattering data provides direct access to the individual atomic displacements responsible for these excitations. Applied to the molecule-based frustrated magnet with a potential magnetic valence-bond state, LiZn2Mo3O8, this approach allows direct assignment of the constrained rotational mode of Mo3O13 clusters and internal modes of MoO6 polyhedra. We anticipate that coupling this well known data analysis technique with dynamic pair distribution function analysis will have broad application in connecting structural dynamics to physical properties in a wide range of molecular and solid state systems.
authors.affiliation: Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, USA.
authors.forename: A M
authors.initials: AM
authors.lastname: Fry-Petit
authors.affiliation: Department of Applied Physics, Cornell University, Ithaca, New York 14853, USA.
authors.forename: A F
authors.initials: AF
authors.lastname: Rebola
authors.affiliation: Institute for Quantum Matter and Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, USA.
authors.forename: M
authors.initials: M
authors.lastname: Mourigal
authors.affiliation: Institute for Quantum Matter and Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, USA.
authors.forename: M
authors.initials: M
authors.lastname: Valentine
authors.affiliation: Institute for Quantum Matter and Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, USA.
authors.forename: N
authors.initials: N
authors.lastname: Drichko
authors.affiliation: Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, USA.
authors.forename: J P
authors.initials: JP
authors.lastname: Sheckelton
authors.affiliation: Department of Applied Physics, Cornell University, Ithaca, New York 14853, USA.
authors.forename: C J
authors.initials: CJ
authors.lastname: Fennie
authors.affiliation: Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, USA.
authors.forename: T M
authors.initials: TM
authors.lastname: McQueen