DENSITY-FUNCTIONAL CORRECTION OF RANDOM-PHASE-APPROXIMATION CORRELATION WITH RESULTS FOR JELLIUM SURFACE ENERGIES

Since long-range electron-electron correlation is treated properly in the random phase approximation ~RPA!, we define short-range correlation as the correction to the RPA. The effects of short-range correlation are investigated here in the local spin density ~LSD! approximation and the generalized gradient approximation ~GGA!. Results are presented for atoms, molecules, and jellium surfaces. It is found that ~1! short-range correlation energies are less sensitive to the inclusion of density gradients than are full correlation energies, and ~2! short-range correlation makes a surprisingly small contribution to surface and molecular atomization energies. In order to improve the accuracy of electronic-structure calculations, we therefore combine a GGA treatment of short-range correlation with a full RPA treatment of the exchange-correlation energy. This approach leads to jellium surface energies close to those of the LSD approximation for exchange and correlation together ~but not for each separately!. @S0163-1829~99!01315-6#