Factorization of 3‐Point Static Structure Functions in 3D Yukawa Liquids

Abstract

AbstractIn many‐body systems the convolution approximation states that the 3‐point static structure function, S(3)(k1, k2), can approximately be “factorized” in terms of the 2‐point counterpart, S(2)(k1). We investigate the validity of this approximation in 3‐dimensional strongly‐coupled Yukawa liquids: the factorization is tested for specific arrangements of the wave vectors k1 and k2, with molecular dynamics simulations. With the increase of the coupling parameter we find a breakdown of factorization, of which a notable example is the appearance of negative values of S(3)(k1, k2), whereas the approximate factorized form is restricted to positive values. These negative values – based on the quadratic Fluctuation‐Dissipation Theorem – imply that the quadratic part of the density response of the system changes sign with wave number. Our simulations that incorporate an external potential energy perturbation clearly confirm this behavior. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)