G4 accuracy at DFT cost: unlocking accurate redox potentials for organic molecules using systematic error...

Area of Science:

• Computational Chemistry
• Theoretical Chemistry
• Physical Chemistry

Background:

• Redox potential is crucial for understanding chemical and biochemical processes.
• Density functional theory (DFT) often struggles to achieve chemically accurate redox potentials due to sensitivity to functional choice and inherent errors.
• Existing DFT methods show large error ranges for computed redox potentials.

Purpose of the Study:

• To develop a cost-effective computational protocol for accurately predicting redox potentials of organic molecules.
• To improve the accuracy of theoretical redox potential calculations beyond standard DFT limitations.
• To assess the performance of the new protocol against experimental and high-level theoretical data.

Main Methods:

• Introduction of the CBH-Redox protocol, an extension of the connectivity-based hierarchy (CBH) method.
• Utilizing effective error cancellation schemes within the computational protocol.
• Testing the CBH-Redox protocol on 46 organic molecules containing C, O, N, F, Cl, and S atoms.
• Comparison of CBH-Redox results with experimental data and G4 theoretical calculations.

Main Results:

• The CBH-Redox protocol achieved near-G4 accuracy for thermochemical data.
• Mean absolute errors (MAEs) for eight tested density functionals were within 0.09 V of experimental and G4 values when using CBH-Redox.
• Six of the eight functionals showed MAEs of 0.05 V or below compared to G4.
• Application of the CBH correction reduced the error range across functionals from ~0.13 V to ~0.04 V.

Conclusions:

• The CBH-Redox protocol offers a significant improvement in the accuracy of calculated redox potentials for organic molecules.
• This method provides a cost-effective way to obtain reliable redox potential predictions.
• The protocol demonstrates effective error cancellation, enhancing the predictive power of DFT for redox properties.