Relativistic atomic level calculations with nuclei carrying additional fractional charges

One-electron energy levels and wavelengths have been calculated for Na-like ions whose nuclei carry quarks with additional charges +-e/3, +-2e/3. The calculations are based on relativistic self-consistent field procedures. The deviations from experimental values exhibit regularities which allow an extrapolation for the wavelengths of 3s-3p, 3s-4p, 3p-3d, and 3p-4s transitions for the nuclear charge Z=11+-1/3, +-2/3. A number of transitions are found in the region of visible light which could be used in an optical search for quark atoms. (orig.)