Future improvements in fitting procedures should focus on cooptimisation of the electrostatic parameters (currently the AM1-BCC charge model is employed without change). Closer examination of the intramolecular, short-ranged properties of the DE potential may also lead to adjustments to, for example, the treatment of 1-4 interactions and improvements in conformational energetics. Here, we started the training procedure of DE-FF from initial ε and r m parameters (eq 2) from the Sage LJ library, which may place limits on the achieved accuracy if parameter space is not adequately explored. In this regard, it may be beneficial to use more advanced, QM inspired func-tional forms as starting points , as we explored for the DE-B68 water model . To facilitate community exploration of new force field functional forms, we have made all software required to derive and use the designed force fields freely available at .