For this reason, GCMC provided the chemical potential of unbound CO 2 dissolved in liquid ammonia. The second step considers the free energy to chemically bind the CO 2 already dissolved in liquid ammonia, following the same enhanced sampling procedure discussed at the beginning of this section. The integration of GCMC with enhanced sampling can thus provide the chemical potential to bind CO 2 in liquid amines directly from air, a quantity of interest to CO 2 adsorption experiments.