where ∆G self i,i is the solute "self"-solvation free energy, R is the molar gas constant, and v i and v j correspond to the pure liquid molar volume of component i and j, respectively. The difference ∆G solv i,j -∆G self i,i is equivalent to the transfer free energy of i from a solution of pure i to pure j (in which it is infinitely dilute). When i = j we obtain the correct limiting behavior that γ ∞ i,j = 1. The self-solvation free energy, ∆G self i,i , may readily be calculated by performing a solvation free energy calculation for component i in itself. Alternatively, we can relate ∆G self i,i to the pure liquid fugacity of component i, f 0 i , as :