This variable controls which form of self-interaction correction to use. Note that
this correction will be applied to the functional chosen by XCFunctional.
Options:
sic_none:
No self-interaction correction.
sic_pz:
Perdew-Zunger SIC, handled by the OEP technique.
J. P. Perdew and Alex Zunger, Phys. Rev. B 23, 5048 (1981)
Extension to the spinor case follows Tancogne-Dejean et al., J. Chem. Phys. 159, 224110 (2023)
sic_amaldi:
Amaldi correction term. Not implemeneted for spinors.
E. Fermi and E. Amaldi, Mem. Reale Accad. Italia 6, 119 (1934)
sic_adsic:
Average-density SIC.
C. Legrand et al., J. Phys. B35, 1115 (2002).
Extension to the spinor case follows Tancogne-Dejean et al., J. Chem. Phys. 159, 224110 (2023)