We first validate our CSP methodologies on molecule 1, the predicted energy-density landscape for which is shown in Fig. . The experimental crystal structure is located by the CSP search as the global lattice energy minimum. An overlay of the predicted global minimum with the experimental crystal structure is shown in Fig. , with comparison of the lattice parameters given in Table . The small root-mean-squared deviation in atomic positions from a 20-molecule cluster from the crystal structure (RMSD 20 =0.269 Å, Fig. ) and good agreement in lattice constants between the experimental and predicted crystal structure demonstrates excellent performance of our force field energy model. The low energy region of the crystal structure landscape for molecule 1 (Fig. ) is dominated by the γ-type of packing, featuring stacking of the planar molecules in columns (Fig. ). Hydrogen bonds are formed between these columns, arranging them into a 'cruciform' pattern in the lowest energy structure. A few sheet-like structures are also present at low energy. Herringbone packing, as seen in the parent [5]phenacene (picene) crystal structure, is strongly disfavoured for molecule 1.