Strange excitations while using desy

[Kwiatkowski]

I'm working on determination of the plasmon excitations of spheres of different sizes.

I did the calculations for it using desy getting either the symmetry oh or d4h.
The excitations of all but one symmetry groups had a oscillator strength of 0.0 and the rotatory strength was 0.0 far all excitations.

If I used the symmetry group c1 all excitation had non-zero oscillator and rotatory strengths (with a great variance of values) and the resulting excitations were different from before.

Does anyone know, why the results differ that way?

[christof.haettig]

maybe a matter of convergence thresholds.
If you run in C1 selection rules will only be fulfilled within numerical convergence of the structure, orbitals and densities. Large systems require often tighter thresholds.