Neutron spectroscopy and QC modeling of methyl dynamics in 1-and 2-methyl-naphthalene crystals

Vibrational densities of states of solid 1- and 2-methyl-naphthalene were o btained from the incoherent inelastic neutron scattering (IINS) spectra mea sured on the NERA spectrometer at the IBR-2 pulsed reactor in Dubna. Calcul ated spectra of the low-frequency vibrations of both studied molecules are compared with the experimental ones. Rotations of methyl groups were found to be affected by intermolecular interactions in the crystals and mixed wit h the lattice modes and naphthalene rings deformations. (C) 2000 Elsevier S cience B.V. All rights reserved.