POTENTIAL-ENERGY SURFACES OF SODIUM CLUSTERS

We have calculated multidimensional Born-Oppenheimer energy surfaces o f singly charged and neutral sodium clusters with quadrupole, octupole , and hexadecapole deformed shapes in a particle range from 8 less tha n or equal to N less than or equal to 58. We use the local-density app roximation (LDA) and solve the Kohn-Sham equations on a cylindrical me sh for axially symmetric shapes. Employing the structure-averaged jell ium model (SAJM), we ascertain that the correct empirical bulk propert ies and surface tension are reproduced. Besides a pronounced isomerism in the beta(2)/beta(4) plane we also find super-deformed shapes. We c ompare the PES data with shape transitions deduced from experimental s plittings of the dipole-photoabsorption cross sections. The influence of large octupole moments reverts the scheme of prolate-oblate shape t ransitions above the filled 2p-shell (Ar = 42,44) which is wrongly pre dicted in spheroidal models.