The smirnoff-plugins interface with the OpenFF software stack now enables us to generate such a DE-based force field for small, organic molecules automatically and robustly, so we did so here. We started a non-bonded parameter fit from the set of ε and r m for 15 SMIRKS types from the recent LJ-based OpenFF Sage force field which are explicitly exercised by the available training data (Figure ). We note that an additional 20 SMIRKS types, including those covering S, P, I, F and counter-ions, were therefore not optimised in this first study, but can be added in future using the procedures described here. Water parameters and the global α and β parameters were initialised to their values from the optimised DE-B68 model, but allowed to vary. The Sage condensed phase mixture set (Section 4.2) was used for training, which includes 555 pure and binary densities, and 477 enthalpies of mixing. In addition, pure water densities at a range of temperatures were included as targets to ensure the water model remained accurate. Bonded parameters were assigned using the Sage small molecule force field, and electrostatics were treated using the AM1-BCC charge model 29 generated using the OpenEye toolkits . We note here that co-optimisation of the small molecule and water force fields is not commonly performed, and some of the improvement in Table may be due to this approach. For example, the Sage force field uses the standard TIP3P water model, with fixed parameters. A comparison of properties of water mixtures is given in Section S2, and confirms that the strong performance of DE-FF on the enthalpy of mixing training set is due in large part to improved descriptions of water -small molecule interactions. Figure further demonstrates that the overall accuracy of the water force field (tested on pure water properties) does not deteriorate significantly upon re-optimisation of the global α and β parameters, and is still suitable as a water model.