Implementation of Perdew-Zunger self-interaction correction in real space using Fermi-Löwdin orbitals.

Area of Science:

• Quantum Chemistry
• Computational Materials Science

Background:

• Density functional approximations commonly exhibit self-interaction error.
• Perdew-Zunger (PZ) self-interaction correction (SIC) is a key method for mitigating this error.
• Existing implementations may lack scalability and systematic convergence.

Purpose of the Study:

• To implement and verify a novel size-extensive formulation of PZ-SIC using Fermi-Löwdin Orbitals (FLOs) in real space.
• To assess the accuracy of this new formulation for molecular properties and reaction barriers.
• To compare the real-space FLOSIC results with existing implementations and experimental data.

Main Methods:

• Implementation of a size-extensive PZ-SIC formulation using real-space FLOs.
• Calculation of atomization energies and ionization potentials for selected molecules.
• Verification using the generalized Slater scheme and comparison with Gaussian-based FLOSIC codes.
• Analysis of scaled Slater statistical averages of SIC potentials.
• Computation of chemical reaction barrier heights for the BH6 dataset.

Main Results:

• The new real-space FLOSIC formulation shows good agreement with existing methods.
• Results obtained using the real-space formulation are closer to experimental values on average.
• Scaling down the average SIC potential further improves accuracy for atomization energies and ionization potentials.
• Significant improvements in chemical reaction barrier heights were observed compared to Gaussian-based FLOSIC.

Conclusions:

• The real-space, size-extensive FLOSIC formulation is accurate and efficient.
• This method offers systematic convergence and scalability for large systems.
• The approach provides improved predictions for molecular properties and reaction energetics, advancing density functional theory accuracy.