The effect of self-interaction error on electrostatic dipoles calculated using density functional theory.

Area of Science:

• Computational chemistry
• Quantum chemistry
• Theoretical chemistry

Background:

• Spurious electron self-interaction in density functional approximations (DFAs) leads to inaccuracies in predicting molecular charge transfer.
• These inaccuracies manifest as errors in calculated electrostatic dipoles for heteronuclear molecules.

Purpose of the Study:

• To quantify the magnitude of self-interaction errors on dipole moments for a diverse set of molecules.
• To evaluate the effectiveness of self-interaction correction (SIC) methods in improving dipole moment calculations.

Main Methods:

• Calculated dipole moments using Perdew-Wang (PW92), Perdew-Burke-Ernzerhof (PBE), and Strongly Constrained and Appropriately Normed (SCAN) approximations.
• Employed the Fermi-Löwdin orbital self-interaction correction (FLO-SIC) approach for corrected calculations.
• Compared DFA and FLO-SIC-DFA results against accurate wave function-based reference values.

Main Results:

• Self-interaction correction generally increases charge transfer and dipole moment magnitudes.
• FLO-SIC-PW92 and FLO-SIC-PBE show improved agreement with reference values, particularly for ionic molecules.
• Applying FLO-SIC to SCAN did not consistently improve dipole values; however, it improved description for stretched bonds and recovered the correct separated atom limit.

Conclusions:

• Self-interaction correction is crucial for accurate dipole moment calculations, especially for ionic systems.
• Optimizing molecular geometries with FLO-SIC-DFA prior to dipole calculation yields the best agreement with reference data.
• FLO-SIC offers a viable route to mitigate self-interaction errors in electronic structure calculations.