Density of phonon states in solid parahydrogen from inelastic neutron scattering

We have measured the inelastic neutron scattering spectrum of solid parahydrogen (at low pressureand T=13.3 K) using the thermal original spectrometer with cylindrical analyzers spectrometer atthe ISIS pulsed neutron source (UK). From the experimental spectrum we have obtained theparahydrogen density of phonon states which has been compared with the estimates available in theliterature. The present determination improves substantially the previous experimental scenariofrom the point of view of both statistics and accuracy. The comparison with the most recent estimateobtained from a quantum mechanical simulation of the molecular dynamics calls for animprovement of the computational methods.