Influence of the exchange-correlation potential in density-functional calculations on polarizabilities and absorption spectra of alkali-metal clusters - art. no. 063201

All-electron calculations in large basis sets of excitation energies, oscil lator strengths, and polarizabilities of small alkali-metal clusters of Li, Na, and K, with up to eight atoms, are performed using time-dependent dens ity-functional theory. It is shown that the use of the recently developed s tatistical average of orbital potentials (SAOP) exchange-correlation (chic) potential [P.R.T. Schipper et al., J. Chem. Phys. 112, 1344 (2000)] leads to polarizabilities of these alkali-metal clusters which are 10-15% larger than polarizabilities calculated with the re potential of the local-density approximation (LDA). The lower LDA polarizabilities (in comparison to the SAOP) are shown to originate from differences in the low-lying excitation e nergies, which are determined by the re potential in the molecular inner an d valence region. In spite of such differences, both SAOP and LDA results a re shown to provide reliable assignments of the experimental absorption spe ctra, with typical errors in peak positions of only 0.1-0.2 eV, or even les s.