DIELECTRIC RESPONSE OF THE DEGENERATE PLASMA OF CHARGED BOSONS IN STATIC-LOCAL-FIELD APPROXIMATIONS

The dielectric screening function epsilon(kappa, omega) of the fluid o f charged bosons at zero temperature is evaluated in a range of low-to -intermediate coupling strength, in view of recent data on static scre ening and fluid structure from quantum Monte Carlo methods. Correlatio ns beyond the random phase approximation are included within a class o f approximations which are well known for the electron fluid, i.e. by introducing a frequency-independent local field factor to be determine d through self-consistency requirements connecting various aspects of the physics contained in the dielectric function. The static dielectri c function epsilon(kappa, 0) is negative over a range of wavenumbers a t all values of the density, leading to oscillatory screening of a for eign charge and to an effective long-range attraction between equi-cha rged impurities. Quantitative agreement with the Monte Carlo data on s tatic screening is achieved by imposing self-consistency on the compre ssibility of the fluid in addition to self-consistency on the pair dis tribution function. Good agreement is also obtained on the pair distri bution function and the correlation energy. Within the present class o f approximations, the dispersion relation of longitudinal excitations takes the Feynman form, starting at the plasma frequency with a negati ve dispersion coefficient and going through a minimum before ending at the single-particle recoil frequency.