Of the molecules studied in this paper, crystal structures of naphthalene and [n]helicenes with n = 3 -7, 9 -11 have been synthesised with more than one polymorph obtained for [5]helicene helicene. With the exception of [3]helicene, X-ray crystal structures were deposited to the Cambridge Structural Database (CSD), which we used to compare to the structures within our CSP landscapes. We found that the CSP landscapes (Fig. ) were able to reproduce most of the experimentally known crystal structures. In instances where this was not the case (n = 5, 6, 7, 9), the experimental structure was either an intergrowth (as with [6]helicene, where the crystal structure contains alternating layers of the opposite helicene enantiomer 60 ) or possessed a higher number of molecules in the asymmetric unit. For example, [5]helicene has two polymorphs (DBPHEN03 and DBPHEN04) where Z ′ = 2 and 3 respectively, [7]helicene has one polymorph (IMEJIW) where Z ′ = 2, and [9]helicene has one polymorph where Z ′ = 3 (QUJNEQ). By construction of our approach, polymorphs with Z ′ > 1 could not be found here as they significantly more computationally expensive. Calculating the energies of these experimental structures and including them in our CSP landscapes lead to the correct assignment of the experimental structure as the lowest energy structure (Fig. ). Representative configurations of the low energy polymorphs-both enantiopure and racemic-for each of the CSP landscapes are shown in Fig. . If a Z ′ = 1 structure had been experimentally realised (with the exception of [4]-and [7]helicene, which will be discussed in detail) our B86bPBE-XDM calculations correctly identified the structure as the lowest energy Z ′ = 1 polymorph within the landscape (Section S1) (Fig. ). Due to the nature of the non-covalent interactions between the molecules, use of DFT is critical for the correct assignment of polymorphs as calculations using DMACRYS often ranked the experimental polymorph higher in energy (Section S2). The only case where a experimentally realised Z ′ = 1 polymorph was not produced in the generation of crystal structures is for [5]helicene, where the racemic DBPHEN02 is missing. However, another synthesised Z ′ = 1 racemic polymorph, DBPHEN05, is predicted, and is lower in energy than DBPHEN02. For [4]helicene, the landscape contains three polymorphs with Z ′ = 1 that are lower in energy than the experimental Z ′ = 1 polymorph. This is because the lower energy polymorphs are racemic, whereas the experimentally realised crystal structure is enantiopure.