CALCULATION OF THE GROUND-STATE ENERGY V(0) OF QUASI-FREE POSITRONS IN RARE-GAS FLUIDS

The energy V0 of the bottom of the conduction band (relative to vacuum) of quasifree positrons in rare-gas fluids is calculated as a function of fluid density. The calculations are performed within the framework of the Wigner-Seitz approximation [Phys. Rev. 43, 804 (1933)] for nonpolar fluids, using a semiempirical analytical potential to model the positron-rare-gas-atom interactions. For all the rare gases studied, V0 is negative and decreases almost linearly with increasing density. Extended to the solid-phase density range, our V0 calculations are in good agreement with available experimental data for rare-gas crystals.