The energy ranking of the sets of force field predicted crystal structures for each molecule has been assessed using a 'single-point' energy correction: a re-calculation of the lattice energy using a fragment-based correction to the force field energy, without further structural re-optimization. The fragment-based energy model tested in this study has a similar form to the HMBI scheme , where the lattice energy is calculated as a force field (ff ) lattice energy, with significant two-body terms corrected to a higher level (hl ) of theory,