The ratio of the weights of the double-excitation amplitudes (t2) and the single-excitation amplitudes (t1) in the first-order wave function provides an internal criterion informing on the reliability of the ADC(2) and CC2 methods. This ratio is shown in Fig. for the S1 state (full symbols) and T1 state (open symbols) for the CBN_1 and CBN_2 ribbons (see Section 3) as function of the number of units. For all systems investigated in the present work, this ratio is in the range of 0.12 -0.14 for the singlet excited states and 0.10 -0.12 for the triplet excited states. It increases only moderately with the number of units, see Fig. .