Collective translational vibrations of n-nonadecane molecules incorporated within the channels of urea inclusion compounds are investigated at 180K by molecular dynamics simulation. Incoherent inelastic neutron scattering (INS) profiles are calculated from the simulation trajectories and compared to experiment. The results allow interpretation of the peaks in the low-energy INS spectrum. Intermolecular intrachannel vibrations of the guest n-nonadecane molecules along the channel axis give rise in the simulation to a peak in the density of states at approximate to 20 cm(-1), the cutoff frequency of the corresponding longitudinal acoustic mode propagating along the channel axis. This is assigned to the experimental peak at approximate to 23 cm(-1). At lower wave numbers a peak in the dynamic structure factor arises from the relative displacements of host and guest substructures (i.e., the rigid-body sliding of the array of alkane molecules within the channels).