While the performance is slightly improved, the parameter changes are more significant when compared to the simulation-only optimization. The changes in parameter value from OpenFF 1.0.0 are shown in Figure . Again, the changes in parameters are larger for the multi-fidelity optimizations when compared to the simulation-only optimization, particularly for the values of 𝜖. However, when compared to the multi-fidelity optimization against "pure only", the changes are smaller and there are not significant outliers. We see some of the same parameter trends as in the "pure only" optimizations, like reduced values of 𝜖 for the [#1:1]-[#6X4] and [#8X2H0+0:1] atom types. A notable difference is the increased 𝑅 𝑚𝑖𝑛∕2 for the [#8:1] type, which is likely related to mixture properties better capturing the hydrogen bond donor/acceptor behavior of alcohol/ester mixtures.