Where f 's are unitless reduced free energies, defined by f = G/RT for all corresponding free energies. We therefore need the natural log of the ratio of the compressibility factors corresponding to the states i and j, ln Z ij to compare the simulated and experimental Gibbs energies. Thermodynamic properties using dimensionless free energies estimated using MBAR are evaluated using the derivative expressions as shown in Table . We note that pressure derivatives can use only the configurational part of the free energy f c , as the reduced kinetic part of the free energy is pressure independent, but temperature derivatives must use the full free energy, as the reduced kinetic term is temperature dependent.