Mixture densities were simulated with a similar workflow to the pure liquid simulations, but with the molecules in the initial box split proportionally between the two chemical species according to the experimental mole fraction. Densities of binary mixtures are straightforward to calculate as they do not require more than one simulation; the process is the same as for densities of single component liquids. Binary enthalpies of mixing are calculated according to equation 2, where the enthalpies of the individual simulated components ( 1 , 2 ) are multiplied by their mole fractions in the mixture, and then subtracted from the enthalpy of the simulated mixture