Density, isobaric and isometric heat capacities, isothermal and adiabatic compressibilities, isobaric thermal expansion coefficient and thermal pressure coefficient are well-studied response functions for fluids. Of these density, isobaric heat capacity, isothermal compressibility, and isobaric thermal expansion coefficient, along with the heat of vaporization, are most commonly used to characterize water models. We can estimate the properties either using a) fluctuation formulas based on ensemble averages or b) derivatives of Gibbs free energy with respect to temperature and pressure. Almost all water model studies use fluctuation formulas to calculate properties. However, we will use the derivatives of free energy using finite difference calculated using reweighting, as we can propagate the error more easily than can be done with the fluctuation formulas. All fluctuation formulas and their derivative versions have been compiled in Table . Derivatives of free energy with respect to pressure or temperature can be computed numerically and the calculation is made trivially cheap by reweighting, since reweighting at different temperatures and pressures requires no additional energy calculations.