where, again, m = [0 -4] and n = 4 -m. Clearly, the reactions above differ in the number of water molecules released upon cluster formation (six in the tetrahedral case versus four in the octahedral environment). Since calculations are performed in the gas phase, this scheme can introduce substantial artificial differences when evaluating entropic factors due to the additional translational and rotational degrees of freedom when more water molecules are released. This can, in turn, lead to an over-stabilization of tetrahedral clusters with respect to octahedral ones.