Phonon dispersion curves in an argon single crystal at high pressure by inelastic x-ray scattering - art. no. 224306

The phonon dispersion of fee argon under high pressure to 20 GPa has been m easured along the (100) direction by inelastic x-ray scattering. First, thi s shows a novel possibility to investigate the single crystal dynamical pro perties under very high pressure in a diamond anvil cell. Second, the compa rison between experiment and phonon calculations, using pair potentials (ei ther the pure two-body potential or an effective pair potential) and a Slat er-Kirkwood form for the three-body interaction, clearly demonstrates that phonon energies can be strongly influenced under high pressure by the nonad ditive part of the interaction.