Simplified implementation of self-interaction correction in sodium clusters

In density-functional theory, the standard Perdew-Zunger method of self-interaction correction leads to exchange-correlation (xc) potentials that are orbital-dependent. We study various simplified implementations of self-interaction correction—derived in the framework of the so-called optimized effective potential method—that lead to a single, orbital-independent xc potential. The performance of the various self-interaction corrected functionals is tested for sodium clusters: we first consider a variety of ground-state properties (total energies, Kohn-Sham orbital eigenvalues, and ionic potential curves) and then study the dynamical regime of weak and strong electronic excitations. It turns out that for sodium clusters the simplest, global-averaging scheme gives a good description of static and dynamic properties, even in the regime of strong excitations.