Symmetries and SAXS/WAXS. (a) Shown is the construction of test nanocrystal structures obeying each of the eight allowed steric zipper symmetries, which are expected to give eight distinct scattering signatures. (b) Shown is the WAXS of the ILQINS peptide solution recorded after 24 h of self-assembly (black) and the calculated scattering for MD snapshots of 1296-peptide nanocrystals (6 × 12 × 18) taken at 10 ns (AP 5, blue; P 1, red). The AP lattice parameters are a = 20.6 Å, b = 19.1 Å, and γ = 82°; the peaks relevant to the lattice shape are annotated with the corresponding Bragg spacing (main and inset). (c) Overlapping regions of the SAXS/WAXS curves are annotated by the type of information that they provide (shape, structure, and solvation). The designed AP structure has extremely good agreement in the structural region with a WAXS curve taken in 2014 and also quite good agreement with these WAXS data. The designed class 1 structure also captures some features of these WAXS data. To see this figure in color, go online.