Papers by Valentina Tozzini
A simple relation is demonstrated between the phonon dispersion curves of crystalline 4He in both... more A simple relation is demonstrated between the phonon dispersion curves of crystalline 4He in both the h.c.p. and the b.c.c. phase near melting and the dispersion law of elementary excitations in the superfluid phase near freezing. The collective dynamics as seen in neutron inelastic-scattering experiments from all these phases near coexistence reflects primarily the static density response function of the liquid and a suitably defined Debye-Waller factor. It is further pointed out that the curvature of the dispersion law at the roton minimum in the liquid is approximately related to the c44 shear elastic constant of the b.c.c. phase.
The cross-over from hydrodynamic to fast sound in water at 5 C has recently been mapped experimen... more The cross-over from hydrodynamic to fast sound in water at 5 C has recently been mapped experimentally by means of inelastic X-ray scattering. We show that a viscoelastic model gives a good account of both the longitudinal-current autocorrelation function and the dynamic structure factor in the region of the cross-over. Evidence is also given for a weakly dispersing excitation observed in these experiments being a liquid state remnant of an oxygen-related optic mode in ice.
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Papers by Valentina Tozzini