Although the alkyl side chain itself does not directly contribute to the spectra of monomers, it has a significant effect on stacking arrangements of aggregates. Fig. displays the crystal structures of DPND6 and DPND 14 from the experimental measurements, where the relative displacements of corresponding dimer are presented. In both crystals, these normal one-dimensional direction with respect to the horizontal direction dominates the spectra and dynamics processes because the interactions between two columns are much weaker than those between monomers along this direction. In dynamic simulations, we thus only consider the one-dimensional molecular chain.