Relations between the longitudinal and transverse sound velocities in strongly coupled Yukawa fluids

Two useful relations between the longitudinal and transverse sound velocities of the strongly coupled single component Yukawa fluids are derived. The first relates the sound velocities given by the quasilocalized charge approximation (QLCA) to the excess pressure of the system. This is shown to be a mathematical identity within QLCA, applicable to any soft isotropic interaction potential. The second relates the same quantities to the fluid sound velocity obtained via the thermodynamic route. Both three-dimensional and two-dimensional cases are considered. The accuracy of the relations is verified using the available results based on direct numerical simulations. (C) 2016 AIP Publishing LLC.