Benchmarking the AK13 Exchange Functional: Ionization Potentials and Electron Affinities.

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Density-Functional Theory

Background:

• Accurate calculation of ionization potentials and electron affinities is crucial in chemistry.
• Semilocal functionals in density-functional theory (DFT) often struggle with the correct asymptotic decay of the exchange-correlation potential.
• Improved asymptotic behavior is desired for more accurate electronic structure calculations.

Purpose of the Study:

• To benchmark various semilocal exchange-correlation functionals in DFT for ionization potential and electronic affinity.
• To evaluate a new generalized gradient approximation for exchange with improved potential decay.
• To assess the trade-offs between energy accuracy and potential accuracy for different DFT functionals.

Main Methods:

• Benchmark calculations for ionization potential and electronic affinity of atoms and small molecules.
• Utilized several semilocal exchange-correlation functionals within DFT.
• Focused on a new generalized gradient approximation (GGA) for exchange with improved asymptotic potential behavior.

Main Results:

• The new GGA functional yielded less accurate energies compared to traditional functionals.
• Potentials derived from the new functional were less accurate than those from functionals modeling the exchange-correlation potential directly.
• The new functional demonstrated a good balance between energy and potential quality.

Conclusions:

• The evaluated generalized gradient approximation offers a compromise for applications needing both reasonable energies and accurate potentials.
• This functional presents a viable option for DFT calculations where a balance of properties is essential.
• Further research may explore refinements to enhance both energy and potential accuracy simultaneously.