FIT and W99rev are two force fields that are commonly used in modelling molecular organic crystals. Both of these force fields are parameterized against structural and energetic information from known crystal structures, and were developed to function in tandem with anisotropic atomic multipole electrostatics. Using atomic multipoles has clear benefits over using isotropic point changes: they result in a more accurate electrostatic model due to the difference in the quality of the representation of electrostatic features such as π -electron density and lone pairs, which leads to improved performance of structure prediction. The revised version of W99 has been parameterized for use with multipole electrostatics derived from a specific set of combinations of DFT functionals and basis sets: B3LYP/6-31G** and B3LYP/6-311G**. Both of these electrostatic models also have a variant that has been derived from the charge density calculated using a Polarizable Continuum Model (PCM). Applying PCM to the electrostatic model can be used as an approximate treatment of molecular polarization in crystal structure modelling. As discussed, our initial CSPs on ATZ and NTO proved unsatisfactory; the closest predicted match to the experimental structure for both EMs possessed a high relative energy and large geometric deviations. Thus, our testing for the choices of force field and electrostatic model involved performing CSPs on the 10 molecules shown in Figure for Z' = 1 structures. Results for eight out of the ten molecules are summarized in Figure ; ATZ and α-FOX7 are not included in this initial evaluation of force fields because we found that flexibility of the NH 2 groups has an important impact on the results for these crystal structures.