Kinematical Hirshfeld atom refinement has been applied to electron diffraction data for the first time, but the effect of using an aspherical atom model is overshadowed by dynamical scattering effects. Dynamical independent atom model refinement leads to significantly improved structures, suggesting that dynamical refinement is also necessary to obtain the full advantage of using aspherical atom models.

Transferable aspherical atom model dynamical refinement on precession electron diffraction data for 1-methyl­uracil crystals offers superior performance compared with the independent atom model and reveals that the quality of 3D electron diffraction data and dynamical refinement is already sufficient to detect minute variations of the electrostatic potential caused by bonding and intermolecular interactions.

With the currently avalaible 3D ED data it is possible to observe details of electrostatic potential deformations due to chemical bonding in organic crystals. The deformation signal is strong enough to see the benefits of using a more accurate potential model (TAAM) in achieving a better fit of the model to the experimental data.

We apply for the first time the transferable aspherical atom model (TAAM) for the refinement of a metal complex structure against 3D ED data. Our results show that TAAM significantly outperforms the independent atom model (IAM) by more accurately depicting the electrostatic potential, particularly in low-resolution ranges. We found that using TAAM for organic ligands is more important than an accurate description of the metal centre in the refinement against 3D ED data.