Collisionless Sound in Classical Fluids

摘要: The dynamic form factor $S(K,\ensuremath{\omega})$ for a classical fluid is calculated from the linearized Vlasov equation. Following Percus or Zwanzig, effective interatomic potential taken as $\ensuremath{-}kTc(r)$, where $c(r)$ direct correlation function. result simple closed expression with no free parameters except static structure $S(K)$. Using Ashcroft and Lekner's hard-sphere Percus-Yevick results $S(K)$, we calculate inelastic neutron scattering liquid lead. resulting law shows strong qualitative similarity experiment. narrow quasielastic peak observed experimentally not, however, given by calculation. reasons this discrepancy are discussed. An extension of calculations to include phenomenological collision term also presented.