Electronic structure of a self-interaction-corrected lithium cluster

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Abstract
Applying a self-consistent, self-interaction-correction (SIC) procedure to a 15-atom lithium cluster results in a lowering of the valence eigenvalues to about 1.5 eV below those of the local density approximation (LDA), with 1s core-state energies dropping to over 18 eV below the LDA. The lowered Fermi level yields a good approximation to the ionization energy as computed by transition-state theory. A significant broadening of the valence energy range to 95% of a bulk LDA calculation is seen, and some migration of valence-electron density into the cluster occurs as a result of the redistribution of orbital density. Application of the SIC with the LDA orbitals yields eigenvalues very close to those obtained with the self-consistent, corrected orbitals, implying that the LDA orbitals are reasonable substitutions for those of the SIC. Simple arguments show that the largest atomic metal clusters amenable to electronic-structure calculation in the LDA retain non-negligible self-energy errors in the eigenvalues of their free-electron-like orbitals.