Electron affinities in the self-interaction-corrected local spin density approximation

Electron affinities are calculated for first- and second-row atoms in the self-interaction-corrected local spin density approximation (SIC-LSDA). We compare results obtained by the orbital SIC method of Perdew and Zunger to those obtained by a new method which employs orbital SIC for exchange and Stoll’s spin-density SIC for correlation. The latter method exhibits exceptional accuracy in correlation and total energy for neutral atoms and negative ions. The orbital SIC method yields more accurate electron affinities overall. This represents a significant improvement over earlier results which employed a spherical approximation for the orbital densities. Both methods follow the experimental trends closely and yield results within 0.2 eV of experiment. This accuracy is shown to be the result of a striking cancellation of errors between exchange and correlation.