To further quantify the effect of low values of 𝑘, we inspected the eingenspectra (arrays of eigenvalues) of ℱ . To perform this analysis, we studied a set of 20 ligands, taking the first 20 ordered ligands from the representative series analyzed in Fig. . We then generated random designs until we found a solution with a nonzero determinant to floating-point precision. If we did not find a suitable design after 3𝑥10 5 iterations, we terminated the search with the random design at the final iteration and then repeated this procedure three times. From this data, we find a progressive consolidation of 𝜆 𝑖 (ℱ ) towards zero as 𝑘 decreases (Fig. ). Interestingly, as 𝜆 𝑖 (ℱ ) becomes less balanced and more skewed towards zero, optimization becomes more difficult .