Freiman Yu.A., Grechnev A., Tretyak S.M., Goncharov A.F., Hemley R.J. «Sound velocities in solid hydrogen under pressure» Физика низких температур, 39, № 5, с. 548-551 (2013)

We present results of semi-empirical lattice dynamics calculations of the sound velocities in solid hydrogen under pressure based on the many-body intermolecular potential and first-principle density-functional theory (DFT). Both the sound velocities and elastic moduli are in excellent agreement with data from Brillouin scattering measurements while Silvera–Goldman and Hemley–Silvera–Goldman potentials tend to overestimate the sound velocity. It is shown that the stiffer is the potential the greater is overestimated the sound velocity. As was the case for equation of state and Raman-active lattice phonon calculations, the employed many-body potential works well for phases I and II (up to ∼140 GPa while for higher pressures the use of the DFT is preferable.

Strazzulla G. «Crystalline and amorphous structure of astrophysical ices» Физика низких температур, 39, № 5, с. 556-559 (2013)

The structure of water and other ices strongly depends on the temperature at which they formed, e.g., by vapor deposition. It is amorphous if ices are formed at low temperature (e.g., 10–30 K for water ice), or crystalline if the deposition temperature is higher (140–150 K). Ices have a “polycrystalline” structure at intermediate temperatures. The crystalline structure of ices can be damaged up to a complete amorphization by processes such as those due to energetic ion bombardment. Here I describe some experimental results obtained by ion irradiation of water and ammonia ices, two species particularly relevant in astrophysics. The results are discussed in the light of the relevance they have in astronomical environments where the actual structure of the ices depends on a competition between energetic processing that induce amorphization and thermal annealing that favors the transition towards more ordered structures.