Molecule 4 ranks second among the whole set in terms of µ GM , and the corresponding crystal structure is shown in Fig. . 4 adopts a similar γ-type packing as 1 (Fig. ) and a key structural feature that might contribute to such a high electron mobility is a significantly reduced π-stacking distance from 3.465 Å for 1 to 3.402 Å for 4. Molecule 4 is also exceptional because there are no other predicted crystal structures within the 7 kJ/mol lattice energy window of the global minimum. Such large energy gaps between structures are unusual on CSP landscapes and this gives a high confidence that the predicted, high µ e structure would be observed if this molecule was synthesized. Moving on to µ max and ∆E to assess the molecules, molecule 5 is again the lead candidate in the whole set. The crystal structure corresponding to µ max for 5 (Fig. ) possesses similar hydrogen-bonded ribbons as the predicted global minimum. µ max tells us the best property that can be achieved for each molecule if we were able to crystallize the correct structure from the low energy region of the crystal structure landscape. We find that structures with enhanced electron mobilities relative to the global energy minimum are predicted at elevated lattice energies for a significant portion of the screened molecules (Table , Fig. ); the global energy minimum crystal structure rarely gives the best electron mobility. This observation is consistent with our previous investigations on azapentacene molecules, where dimers within crystal structures with significant co-facial overlap (giving rise to largest t and µ) are often energetically penalized by relatively large exchange-repulsion interactions.