where a = nA + 2nAA+ nAB is the total number of molecules of type A put into the solution (equivalently for b); nA, nB, nAA, nBB, nAB are the particle numbers for the five different monomer and dimer species, V is the volume and n is the sum of the particle numbers. The system now minimizes the free energy -kT ln , i.e., it maximizes , by choosing the particle numbers optimally.