Plasma response functions, fluctuation-dissipation relations and the velocity-average-approximation

✍ Scribed by K.I. Golden; G. Kalman

• Publisher: Elsevier Science
• Year: 1982
• Tongue: English
• Weight: 870 KB
• Volume: 143
• Category: Article
• ISSN: 0003-4916
• DOI: 10.1016/0003-4916(82)90217-2

✦ Synopsis

We derive and list relationships for quadratic and cubic static response functions and connect them with three-and four-point functions through generalized fluctuation-dissipation relations. We also introduce the useful concept of "response function of the second kind." to describe the reponse of a system through the perturbation of its two-point functions. Next, we point out that the VAA (velocity-average-approximation) introduced earlier as a part of a dynamical approximation scheme for strongly coupled one-component plasmas is exact in the static limit. This observation, combined with the fluctuation-dissipation relations, allows one to derive a hierarchy of equations for response functions of increasing nonlinearity, which is equivalent to the BGY hierarchy for particle distribution functions.