Modeling temporary anions in density functional theory: calculation of the Fukui function

Area of Science:

• Computational chemistry
• Quantum chemistry
• Theoretical chemistry

Background:

• Modeling temporary anions is crucial for understanding electron-molecule interactions.
• Density functional theory (DFT) is a common method, but accurately modeling anions presents challenges.
• Artificial electron binding is one approach to address these challenges.

Purpose of the Study:

• To investigate two distinct approaches for modeling electron densities of temporary anions within DFT.
• To compare the effectiveness of artificial electron binding using a compact basis set versus a potential wall.
• To determine Fukui functions for nucleophilic attack in molecules with varying electron affinities.

Main Methods:

• Two artificial electron binding strategies were employed: a compact basis set and a potential wall.
• The degree of electron binding was controlled using the negative electron affinity, approximated via DFT local functional frontier orbital eigenvalues and vertical ionization potential (A=-(ε(LUMO)+ε(HOMO))-I).
• Fukui functions for nucleophilic attack were calculated for four molecules.

Main Results:

• Both investigated approaches yielded very similar results for Fukui functions.
• The results obtained with artificial electron binding were significantly different from those calculated without it.
• The potential wall method allows for the use of large, diffuse basis sets, eliminating the need for molecule-specific compact basis sets.

Conclusions:

• Artificial electron binding is an effective strategy for modeling temporary anions in DFT.
• The potential wall approach offers advantages in basis set flexibility.
• The calculated Fukui functions provide insights into nucleophilic attack mechanisms for temporary anions.