Potential energy surfaces of sodium clusters

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 less than or equal to N less than or equal to 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 beta(2)/beta(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 (Ar = 42,44) which is wrongly predicted in spheroidal models.