Extrapolating DFT Toward the Complete Basis Set Limit: Lessons from the PBE Family of Functionals.

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Materials Science

Background:

• Density Functional Theory (DFT) calculations are crucial for predicting molecular and material properties.
• Achieving high accuracy in DFT often requires computationally expensive large basis sets.
• Extrapolation methods offer a way to obtain accurate results from smaller, more affordable basis sets.

Purpose of the Study:

• To develop and validate new formulas for determining extrapolation parameters in DFT calculations.
• To improve the accuracy of DFT results obtained from 2- and 3-ζ basis sets.
• To assess the transferability and performance of these new extrapolation parameters across different DFT functionals and system sizes.

Main Methods:

• Developed formulas for extrapolation parameters that account for the specific density functional approximation used.
• Fitted these formulas to reproduce complete basis set limit energies for PBE and related functionals.
• Evaluated the performance of the derived extrapolation parameters using standard benchmark datasets and large molecular systems.

Main Results:

• The systematically derived extrapolation formulas accurately reproduce high-level theoretical energies.
• The new extrapolation parameters demonstrate improved performance compared to previous methods.
• The [2,3]-ζ extrapolation approach shows robust accuracy for interaction energies, even in large systems with noncovalent interactions.

Conclusions:

• The proposed extrapolation method provides a reliable and affordable route to high-accuracy DFT results.
• The developed formulas are transferable beyond the PBE functional family, enhancing their applicability.
• This approach is particularly effective for studying systems with significant noncovalent interactions, regardless of size.