Anomalous behavior of plasma response functions at strong coupling

Using data from equilibrium Molecular Dynamics computer simulations we have built up a catalogue of response functions for the Coulomb one-component plasma (OCP) over wide range $\Gamma$ coupling values, including strongly coupled $\Gamma > 1$ liquid regime. We focus on domain negative compressibility ($\Gamma>3$), where causality and concomitant Kramers-Kronig relations are violated. give description details violation, both in frequency time domains. show that viscoelastic pole density function morphs into an imaginary upper $\omega$ half-plane is responsible anomalous behavior this range. By examining plasmon dispersion relation through dielectric function, rather than via peaks dynamical structure obtain more reliable representation dispersion. demonstrate there intimate link between formation roton minimum system. The feasibility extension our analysis to systems with short interaction explored.