Electron affinity in density-functional theory in the local-spin-density approximation

Ionization potentials for most atoms are described accurately by total-energy differences calculated within density-functional theory (DFT) in the local-spin-density approximation (LSD). Electron affinities cannot be obtained in the same way, because the long-range behavior of the LSD potential is incorrect and negative ions are not bound. Were I show how electron affinities can be accurately estimated taking advantage of the nearly quadratic dependence of the LSD energy on the occupation numbers around the neutral atomic configuration. The procedure yields electron affinities, for plain LSD atoms, in better agreement with experiments than other self-interaction corrected DFT-based results. [S1050-2947(98)03402-7].