Constrained optimization of Fermi-orbital descriptors*

The Fermi-Löwdin orbital self-interaction correction (FLO-SIC) method removes the spurious self-interaction from common density functional theory (DFT) approximations. Within FLO-SIC, Fermi orbitals are used as localized orbitals. Each of these orbitals is constructed using a point in real space, called Fermi-orbital descriptor (FOD). To obtain the minimum total energy, the set of FODs needs to be optimized.
This optimization is challenging and time-consuming. Accordingly, ways to reduce the computational burden are desired. In this work, we present a way to constrain the FODs. We exploit the tendency of the FODs to arrange in symmetrical patterns considering different atomic shells and bonding situations [1].
We will show how such a constrained approach improves the efficiency of the FOD optimization by comparing to an unconstrained approach. Finally, we will discuss applications and future directions.

[1] S. Schwalbe, K. Trepte, et al., JCC, 2019