Deriving the magnitude of the axial component and rhombicity of the alignment tensor from a histogram of normalized RDCs. The data are taken for the protein cyanovirin,173 and the backbone Cα-Hα and Cα-C′ RDCs are normalized relative to the backbone N–H RDCs. The maximum, minimum and mode of the distribution correspond to Dzz = 2Da, Dyy = −-Da(1 + 1.5η), and Dxx = −Da(1 – 1.5η), where Da (scaled for N–H bond vectors) is the magnitude of the axial component of the alignment tensor and η the rhombicity. The sum of the three orthogonal components of the alignment tensor is equal to zero (Dzz + Dyy + Dxx = 0).