Species with negative electron affinity and standard DFT methods. Finding the valence anions

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Theoretical Chemistry

Background:

• Traditional bound-electron DFT models accurately predict negative electron affinities (EA) when a valence anion state is found.
• These models struggle with predicting the lowest EA when the ground anion state is non-valence, with the extra electron in a diffuse orbital.

Purpose of the Study:

• To propose an alternative computational approach for accurately determining the valence anion state.
• To improve the prediction of electron affinities (EA) for molecules where traditional DFT methods fail.

Main Methods:

• An alternative approach based on the stabilization exerted by a polar solvent was developed.
• The methodology involves gradually decreasing the dielectric constant of the simulated polar medium.

Main Results:

• The proposed method successfully finds the valence anion state, leading to correct EA values.
• This approach provides EA predictions beyond the Koopman's theorem approximation.

Conclusions:

• The polar solvent stabilization method offers a reliable way to compute accurate electron affinities (EA).
• This technique addresses a key limitation in current DFT-based electron affinity calculations, particularly for non-valence ground anion states.