Our previous version of QUBEKit relied on an implementation of the DDEC AIM approach in the ONETEP DFT code. The DDEC AIM method is described elsewhere, but in short it aims to construct the optimal weighting factors of eq 2 that result in approximately spherical atomic electron densities, so that its multipole expansion converges rapidly, whilst ensuring that the resulting charges are chemically reasonable. Alongside the observation that DDEC charges show excellent transferability between different conformations of the same molecule, these properties make the DDEC AIM approach very promising for flexible force field design.