where the first term is the interaction energy correction and the second term is the fluctuation correction. The subscript ε DFT indicates that the sampling is over configurations produced by the DFT simulation. As presented in Table , the results of DFT calculations (with the same basis set, pseudo-potential and functional as those in the above simulation) are close to the results of the MP2 calculations obtained with the Psi4 code for the sampled clusters. (Note that in Table the results are presented in reference to the MP2 data; thus, the sign of the energetic correction should be flipped when inserting the data into Eq. 12.) Inclusion of the D2 correction over-estimates the interaction energy by -6.4 kcal/mol on average. As mentioned above, the over-binding between ions is also indicated by the 7% overestimation of the molten NaCl density at 1150K. The PBC interactions (related to the Ewald potential ) for the simulation cell of size 16.0 Å contributes about 10.0 kcal/mol to the interaction energy correction for the solute ion pair, while in the cell of size 25.4 Å it contributes about 2.0 kcal/mol. The distributions of the interaction energy corrections under PBC in the cell of size 25.4 Å are presented in panel d of Fig. .