Firstly, the choice of which force-field parameters to optimise can strongly influence the goodnessof-fit. The Buckingham potential contains three parameters for each interaction as shown in Equation . A commonly held view is that accurate determination of the B parameter through empirical fitting schemes is challenging and may result in overfitting of the potential. This is usually attributed to its strong correlation with the A parameter, as well as the sensitivity of the potential to the B parameter value. Following the lead from previous methodologies , we choose to fix the B parameter of each potential at the values used in the FIT potential, and only estimate the A and C parameters for each species-species interaction. It has also been found in previous investigations that explicitly fitting cross-interactions can lead to better models compared to using combining rules. We choose to follow the same methodology and estimate all cross-interactions explicitly.