Quantum Chemistry for Weakly-Bound Anions

In this section, we discuss the ways in which weakly-bound anions place special demands on quantum chemistry calculations. It is presumed, in this discussion, that the anion M is a bound species (VDE > 0) at the molecular geometry in question, such that the application of bound-state quantum chemistry methodology is appropriate. Referring to the situation in Figure 1, bound-state methods are appropriate for the description of the anion AB only for R > R. For R < R, the neutral molecule is lower in energy, and application of bound-state methods to M is not appropriate. Electronic structure methods for temporary anion resonances are discussed later in this chapter. 

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