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We present ionic geometries of Na9+ and Na55+ which have been calculated in the "cylindrically averaged pseudopotential scheme". By computing the photoabsorption spectra which result from our cluster geometries and comparing them to the experimentally measured ones we obtain a first check for our structure calculations. Underlying our calculations is a local pseudopotential which has been constructed to reproduce atomic and bulk properties of sodium and which can efficiently be handled numerically. By comparing calculations with different pseudopotentials we find that the position of the dipole resonance is greatly influenced by the pseudopotential. This shows that pseudopotentials must be used consistently in both geometry optimization and the calculation of electronic resonances.
ISSPIC9 (Lausanne, September 1998); European Physics Journal D 9, 149 (1999).