Modified regional self-interaction correction method based on the pseudospectral method.

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Electronic Structure Theory

Background:

• Self-interaction errors (SIEs) are a known issue in density functional theory (DFT) calculations, particularly affecting core electronic regions.
• Existing methods like regional self-interaction correction (RSIC) aim to mitigate SIEs but can be improved for accuracy in specific electronic states.

Purpose of the Study:

• To introduce a modified RSIC scheme, termed pseudospectral RSIC (PSRSIC), designed to effectively eliminate SIEs, especially in core electronic regions.
• To evaluate the performance of PSRSIC when combined with the long-range correction (LC) scheme for time-dependent DFT (TDDFT) calculations.

Main Methods:

• Developed the pseudospectral RSIC (PSRSIC) method, which substitutes Hartree-Fock (HF) exchange energy density from pseudospectral calculations into the SI-domain region.
• Integrated PSRSIC with the long-range correction (LC) scheme, creating the LC-PSRSIC methodology.
• Performed TDDFT calculations using the LC-PSRSIC approach to determine various excitation energies.

Main Results:

• LC-PSRSIC successfully reduces self-interaction errors, particularly in core electronic regions.
• Calculations using LC-PSRSIC yielded accurate results for core-, valence-, Rydberg-, and charge-transfer-excitation energies.
• Core-ionization energies were also well-reproduced by the LC-PSRSIC method.

Conclusions:

• The proposed LC-PSRSIC method offers a significant improvement in accurately describing electronic excitation and ionization energies.
• PSRSIC is effective in mitigating self-interaction errors, providing reliable results for challenging electronic states, including core levels.