Immersion of an inert-gas atom or H2 molecule into jellium: Modified electron-gas approach

The immersion energy of an inert-gas atom or H2 molecule into jellium is calculated using an electron-gas approximation. Our modification of the energy functional of Gordon and Kim [J. Chem. Phys. 56, 3122 (1972)] includes a correction to remove the self-exchange term from the exchange energy and adjustments to take into account the nonuniformity of the system. The calculated ratio of the immersion energy to the jellium density varies about a factor of 2 over five orders of magnitude variation in jellium density and agrees relatively well (within a factor of 2) with the result of previous density-functional approaches in the low-density limit; the Gordon-Kim model is not reliable, however.