The repeating units of several structures in Figure can be considered combinations of simpler monomer units. For example, structure 23 can be viewed as a combination of 8 and 15 (Fig. ). Figure illustrates how our calculated energies of smaller polymer units can be used to estimate the relative energies of more complex HCN-based structures through a weighted averaging approach (see the Methods for details). Such linear extrapolation is approximate and can be expected to fail e.g., in the presence of extensive conjugation. Nonetheless this approach constitutes a rapid route to exploring the thermodynamics of a larger structural space of HCN-derived materials.