Binding free energy and thermal contributions to the binding free energy are defined as follows, where i denotes the components of a given cluster. In the first equation, we define the binding free energy as the total free energy of the cluster with the sum of the monomer free energies subtracted. In the second equation, we define the binding free energy as a sum of an electronic binding energy contribution and a thermal binding energy correction. In our scheme the thermal binding energy correction includes both the changes in thermal effects and changes in vibrational zero-point energy.