Velocity-Autocorrelation Function in Liquids, Deduced from Neutron Incoherent Scattering Results

The Fourier transform p(ω) of the velocity-autocorrelation function is derived from neutron incoherent scattering results, obtained from the two liquids Ar and H2. The quality and significance of the results are discussed with special emphasis on the long-time t-3/2 tail, found in computer simulations and recent theories. The available experimental data from Na, Ar, and H2 close to their normal melting points are consistent with calculations which take into account the contribution to p(ω) from the tail at low frequencies.