Symmetry Breaking within Fermi-Löwdin Orbital Self-Interaction Corrected Density Functional Theory

Fermi-Löwdin orbital self-interaction corrected density functional theory (FLO-SIC DFT) is applied to C₃H₅, NO₃^-, O₃, and CH₃. In general our results indicate that FLO-SIC does favor symmetric setups for molecules with nontrivial chemical bonding. Further we discuss two types of possible symmetry breaking. In the case of O₃ a ground state density that breaks symmetry can be found for the symmetric molecular geometry that may be caused by insufficient treatment of correlation energy. The CH₃ radical presents a second type of symmetry breaking were the lowest energy geometry becomes distorted. The latter highlights the importance of further development of approximate DFT functionals as well as further extensions of the FLO-SIC method to overcome such nonphysical artifacts.