SHAPE ISOMERISM OF SODIUM CLUSTERS WITH QUADRUPOLE, OCTUPOLE, AND HEXADECAPOLE DEFORMATIONS IN THE STRUCTURE-AVERAGED JELLIUM MODEL

Multidimensional deformation energy surfaces of singly charged sodium clusters with 8 less than or equal to Z less than or equal to 50 valen ce electrons have been calculated including quadrupole, octupole, and hexadecapole shapes for the ionic background. We solve the Kohn-Sham e quations in the local-density approximation with preserved axial symme try on a two-dimensional lattice. In addition to the diffusivity of th e jellium surface, the structure-averaged jellium model (SAJM) which y ields the empirical bulk properties and surface tension of sodium is s uccessfully applied to deformed systems. Discussing the systematics of shape transitions, we find good agreement with recent experimental di pole resonance splittings found in the photoabsorption cross sections and confirm the oblate shape of the first neighboring clusters above t he closed 2p shell (Z = 40) provided that left-right asymmetry is enab led.