The first groupings investigate the choice of underlying QM methods used to compute the total electron density for AIM partitioning and subsequent non-bonded parameter derivation (the same QM method is also used for Hessian matrix calculation and dihedral scans to obtain the bonded parameters). As mentioned, our first implementation of QUBEKit 29 interfaced with the ONETEP DFT code, which uses the PBE exchange-correlation functional, for non-bonded parameter derivation. However, this new version of QUBEKit is interfaced, via which gives us access to a wide range of alternative quantum chemistry methods. If using PSI4, the electron density partitioning is performed using MBIS. If using Gaussian09, Chargemol is used to calculate the atom centred charges via either the DDEC3 or DDEC6 AIM schemes. In all cases, the AIM method returns atom-centred point charges, the third radial moment of the atomic electron density (for Lennard-Jones parameter derivation), and multipole moments of the atomic electron density (for virtual site derivation).