Potential energy surfaces of sodium clusters

Abstract

We have calculated multidimensional Born- Oppenheimer energy surfaces of singly charged and neutral sodium clusters with quadrupole, octupole, and hexadecapole deformed shapes in a particle range from 8 ≤ N ≤ 58. We use the local-density approximation (LDA) and solve the Kohn-Sham equations on a cylindrical mesh for axially symmetric shapes. Employing the structure-averaged jellium model (SAJM), we ascertain that the correct empirical bulk properties and surface tension are reproduced. Besides a pronounced isomerism in the β ₂/β ₄ plane we also find super-deformed shapes. We compare the PES data with shape transitions deduced from experimental splittings of the dipole. photoabsorption cross sections. The influence of large octupole moments reverts the scheme of prolate-oblate shape transitions above the filled 2p-shell (N = 42, 44) which is wrongly predicted in spheroidal models.