Zero-Point Motion of Liquid and Solid Hydrogen

Abstract

We present an inelastic neutron scattering study of liquid and solid hydrogen carried out using the wide Angular Range Chopper Spectrometer at Oak Ridge National Laboratory. From the observed dynamic structure factor, we obtained empirical estimates of the molecular mean-squared displacement and average translational kinetic energy. We find that the former quantity increases with temperature, indicating that a combination of thermal and quantum effects is important near the liquid-solid phase transition, contrary to previous measurements. We also find that the kinetic energy drops dramatically upon melting of the crystals, a consequence of the large increase in molar volume together with the Heisenberg indeterminacy principle. Our results are compared with quantum Monte Carlo simulations based on different model potentials. In general, there is good agreement between our findings and theoretical predictions based on the Silvera-Goldman and Buck potentials.

20 pages, 10 figures in color, submitted to Phys. Rev. B

References in corpus (5)

• Mantid - Data Analysis and Visualization Package for Neutron Scattering and $\mu SR$ Experiments
• Superfluidity and Quantum Melting of para-Hydrogen clusters
• Microscopic molecular superfluid response: theory and simulations
• Quantum statistics and the momentum distribution of liquid para-hydrogen
• Atomic displacements in quantum crystals

Cited by in corpus (1)

• Phases of ${}^4$He and H${}_2$ adsorbed on a single carbon nanotube