Microscopic collective dynamics in liquidparaH2

Abstract
Well-defined phonons with strong anomalous (upward) dispersion are observed by inelastic neutron scattering in liquid paraH2 at a temperature of 15.7 K. The damping, being very small for the low-Q phonons, increases with wave vector Q, and only broad features are observed for Q1Å1. This behavior is shown to deviate strongly from results of molecular simulations of a fully classical analogue using a realistic potential.