The numerical settings are based on prior work with Cu(111)/TCNE . In detail, we used tight species defaults, as supplied by FHI-aims (prior to 2020) for the carbon and the nitrogen atoms. For the first three layers of the Cu substrate, we used settings that were slightly modified from the shipped "tight" defaults. Specifically, the onset of the cutoff potential is increased to 4.6 Å, the radial multiplier is reduced to 1, the 5g-basis function is omitted and the basis_dep_cutoff is reduced to 1 × 10 -3 Å. The settings for the remaining substrate layers are based on FHI-aims' "light" species defaults for Cu, with the following changes: the basis_dep_cutoff is reduced to 1 × 10 -3 Å, the angular grid divisions are changed to division 0.3478 50; division 0.6638 110; division 0.9718 194, and only the minimal basis with additional 4p functions are used. All settings are carefully tested, see Supporting Information.