Strategies to Calculate Fukui Functions and Applications to Radicals with SOMO-HOMO Inversion

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Theoretical Chemistry

Background:

• The Fukui function is crucial for predicting chemical reactivity.
• Calculating the Fukui function accurately, especially for complex systems like organic radicals, presents challenges.
• Range-separated hybrid functionals offer tunable properties for electronic structure calculations.

Purpose of the Study:

• To develop an efficient and numerically accurate method for computing the Fukui function from fractional orbital occupations.
• To investigate the energy- and density-linearity conditions for Fukui function calculations.
• To study the reactivity of organic radicals, particularly those exhibiting SOMO-HOMO inversion (SHI).

Main Methods:

• Utilized fractional orbital occupation calculations to derive the Fukui function.
• Employed optimally tuned range-separated hybrid functionals.
• Analyzed energy- and density-linearity conditions.
• Computed Fukui functions, radical reaction energies, and vertical ionization potentials.

Main Results:

• Developed a robust procedure for calculating the Fukui function.
• The Fukui function successfully identified reactive sites in the studied organic radicals.
• SOMO-HOMO inversion (SHI) systems require additional computed quantities for differentiation from conventional radicals.

Conclusions:

• The proposed methodology provides an efficient route to the Fukui function.
• Fukui function analysis is valuable for understanding radical reactivity.
• Distinguishing SHI systems necessitates a multi-faceted computational approach beyond just the Fukui function.