In summary, using SAPT and TD-DFT, we can construct a highly accurate potential for water interactions beyond 4Å, with a physical decomposition to the total energy. It is noted that such procedure has been well established by previous works, and can be easily generalized to different molecules with different chemical compositions. On top of this accurate long-range potential, we develop a series of models (labeled from model 1 to model 6, as we introduced in the theoretical background section) with different levels of range separation and test their accuracies and transferabilities. The results will be discussed in the next few sections. C model, in comparison with the CCSD(T) reference. The three scans plotted in black, red, and blue represent the best, the medium, and the worst performers among all the scans, respectively.