Note: Sound velocity of a soft sphere model near the fluid-solid phase   transition
  The quasilocalized charge approximation is applied to estimate the sound velocity of simple soft sphere fluid with the repulsive inverse-power-law interaction. The obtained results are discussed in the context of the sound velocity of the hard-sphere system and of liquid metals at the melting temperature. 
Sergey A. Khrapak
cond-mat.soft cond-mat.mtrl-sci physics.chem-ph