Shape isomerism in sodium clusters with 10≤Z≤44: Jellium model with quadrupole, octupole, and hexadecapole deformations

We present deformation energy surfaces of singly charged sodium clusters with 10<=Z<=44 valence electrons. We use the structurally averaged jellium model with quadrupole, octupole, and hexadecapole shapes of the ionic background. The Kohn-Sham equations in local-density approximation are solved on a two-dimensional grid with axial symmetry. We discuss the systematics of spherical, prolate, and obate found-state shapes and find good agreement with recent experimental information from dipole resonances in photoabsorption measurements. In particular, we confirm the oblate shapes of clusters above the Z=40 closed shell, which only result when octupole deformations are included. For some clusters with Z≥40 we find a static electric dipole moment of order ∼0.01 a.u.