Self-consistency in the Fermi-Löwdin orbital self-interaction correction method using the Krieger-Li-Iafrate approximation*

The Perdew-Zunger (PZ) self-interaction correction (SIC) method provides a way to remove one-electron self-interaction errors on an orbital-by-orbital basis. It requires use of local orbitals as use of Kohn-Sham orbitals leads to the size-extensivity problem. Pederson and coworkers have shown that use of Fermi-Löwdin orbitals (FLOs) simplifies implementation of PZ-SIC. In this talk we present a self-consistent implementation of FLO-PZ-SIC using the Krieger-Li-Iafrate approximation (KLI) to the optimized effective potential (OEP) and compare it to Jacobi-like self-consistent implementation of Pederson et al. [1]. Since a single Hamiltonian is diagonalized in FLO-SIC-KLI it, unlike the Jacobi method, also provides a correction to unoccupied orbitals. We compare the results obtained using the FLO-SIC-KLI method with the FLO-SIC-Jacobi scheme for a wide array of properties. Our results show that FLO-SIC-KLI provides comparable results to the FLO-SIC-Jacobi for a wide array of properties. Similar to the differences between Hartree-Fock and exact exchange OEP HOMO-LUMO gaps, we find that the HOMO-LUMO gaps in FLO-SIC-KLI are smaller than FLO-SIC-Jacobi gaps.
[1] Yang et al., Phys. Rev. A 95, 052505 (2017)