Concerning the applicability of density functional methods to atomic and molecular negative ions

There is concern within theoretical chemistry that density functional methods are fundamentally in error for negative ions. We have tested this hypothesis by evaluating electron affinities for F and F2 with a variety of density functionals and extremely large, diffuse basis sets. In addition, we have observed the behavior of a known unbound system Ne−. We have found no convincing evidence to support the claims of negative ion instability with density functional methods.