Dynamic structure factor of strongly coupled Yukawa plasmas with dissipation

Abstract

The dynamic structure factor (DSF) of the three-dimensional Yukawa one-component plasma is studied with molecular and Langevin dynamics simulations at moderate and strong coupling. The focus of the investigation is on the dependence of the DSF on the friction coefficient in different frequency and wavenumber regimes. At small to intermediate wavenumbers, frictional damping reduces the strength of the sound peak and leads to a red-shift of its frequency. In an intermediate range of friction coefficients, reducing the wavenumber leads to the vanishing of the sound peak at a finite frequency and the formation of a maximum at zero frequency. This is in contrast to simulations without friction, where the characteristic Rayleigh and Brillouin peaks are observed. The Rayleigh peak around zero frequency for systems without dissipation is generally weak. The simulations show that a small amount of friction can initially decrease its height even further before a strong single maximum is formed at strong damping. At large wavenumbers, the DSF of moderately coupled Yukawa plasmas with dissipation is well described by a single-particle model without interactions, provided frictional damping is taken into account.