DENSITY-OF-STATES IN THE DRUDE-LORENTZ MODEL OF A NONPOLAR FLUID

The frequency-dependent self-susceptibility of a selected particle in the Drude-Lorentz model of a nonpolar fluid is shown to have a univers al absorption spectrum in the limit of low density. We derive an expre ssion for the universal lineshape and calculate the limit function by a scaling procedure, in a self-consistent ring approximation. The line shape is found to be an asymmetric function of frequency, as suggeste d by computer simulation data for systems of hard spheres and of atoms with Lennard-Jones interactions. A calculation of correction terms ac counting for the effect of the microstructure at moderate density lead s to fairly good agreement with existing computer simulation data. (C) 1996 American Institute of Physics.