C. An unusual piano-stool complex While the application to a benchmark set does provide useful insight into the general performance of our method, it is of particular interest to reproduce key structural features in different molecular crystals. We took an example from an earlier study. The piano-stool complex A depicted in (Figure ) presents an interesting challenge. High-resolution X-ray data allowed for the localisation of the Cp ring hydrogen atoms in the crys- tal, revealing an uncommon feature. Although the latter is complexed with a Na + , the hydrogen atoms are displaced towards the cation. This is counterintuitive since the hydrogen atoms are expected to be positively charged and thus bending away as it had already been found in early gas phase calculations of related Lithium systems. In our earlier work, we used a fixed crystal lattice and frozen charges to describe the neighboring cells. We were able to show that the angle between the hydrogens and the Cp ring is strongly influenced by the environment and that the structure of the complex converges after two shells of neighboring units are considered. This is caused by a charge accumulation from the ring on the side facing the cation. However, the question remained if when including a more accurate description of the environment the effect would be kept.