In this preliminary report, we have characterized the CAP parameters that are needed to obtain a well-defined harmonic progression that terminates at the appropriate energy cutoff, without spurious peaks at high energy. Absent the CAP, only a few low-energy harmonics can be observed but even when the CAP is activated, spurious peaks may result (coinciding with certain resonances) if the CAP parameters r 0 and η are not set properly. Some of these spurious peaks coincide with excitation energies while other result from ionization channels coinciding with Koopmans ionization energies, -ε k . We find that the turn-on radius for the CAP (parameter r 0 ) primarily affects the cutoff energy at which the harmonic sequence is attenuated, while the curvature parameter (η) controls the noise in the spectrum. Since the cutoff energy can be estimated in advance, the value of r 0 should be modified on this basis. The value of η can then be set to control the noise above the harmonic cutoff.