## Sound velocities in H_2, He, and H_2-He solid mixtures under pressure    [PDF]

Yu. A. Freiman, Alexei Grechnev, S. M. Tretyak, A. F. Goncharov, C. -s. Zha, R. J. Hemley
Bulk and shear sound velocities in solid hydrogen, helium and hydrogen-helium mixtures under pressure are calculated using two complementary approaches: semi-empirical lattice dynamics based on the many-body intermolecular potentials and density-functional theory in generalized gradient approximation. The thermodynamics of the He-H$_2$ mixture has been treated within the additive-volume approximation. Our results are compared with the first-principle diffusion Monte-Carlo calculation of Alavi {\it et al.} (Science {\bf 269}, 1252 (1995)) and the semi-empirical work of Duffy {\it et al.} (Science {\bf 263}, 1590 (1994)) which employs the two-body Young-Ross potential. It is shown that the stiffer the potential is, the more the sound velocity is overestimated. Comparison with the data obtained from the observation of global oscillations of Jupiter is also made.
View original: http://arxiv.org/abs/1308.0913