where 〈𝜒〉 and 〈𝜂〉 are calculated from the principal values of 𝐕 A (cf. Eq. S1), and 𝛽 A→L and 𝛾 A→L are Euler angles de-fining the orientation of the laboratory z axis in the frame of the principal axes of 𝐕 A ; this corresponds to the orientation of the crystallite with respect to the lab frame. The non-zero elements of the decoherence matrix are calculated from: 𝜆 ± (Ω A→L ) = ∫ 〈𝛥𝜈 ±1 (0)𝛥𝜈 ±1 (𝜏)〉 𝑑𝜏 𝑇 0 (7) where Δ𝜈 ±1 (𝑡) = 𝜈 ±1 (Ω P→A (𝑡); Ω A→L ) -𝑣̅ ±1 (Ω A→L ) and the time averaging in Eq. ( ) is performed over rotations in the A frame which are defined by Ω P→A (𝑡). The total rotational transformation from the PAS to the lab frame is defined as: 𝑅(Ω P→L (𝑡)) = 𝑅(Ω A→L )𝑅(Ω P→A (𝑡)). The density matrix is propagated according to Eq. ( ) using standard numerical approaches, and projected onto the detection operator 𝐼 + to generate the NMR signal, s(t), prior to Fourier transformation into the frequency domain. In this simple case, however, the 〈𝐿 ̂〉 and Λ ̂ matrices are diagonal, with the 𝑣̅ ±1 (Ω A→L ) corresponding to the NMR frequencies with associated damping coefficients 𝜆 ± (Ω A→L ). Finally, the response is averaged over 𝛽 A→L and 𝛾 A→L angles assuming an isotropic distribution of crystallites in the sample.