Density-Fitting Method in Symmetry-Adapted Perturbation Theory Based on Kohn-Sham Description of Monomers

With the DF-SAPT(DFT) approach, RDX dimer can be calculated within a reasonable CPU time. This system is beyond the reach of correlated ab initio methods such as CCSD(T). SAPT(DFT) also provides an insight into physical picture of the interactions by decomposing the interaction energy into physical contributions. The analysis of the interaction energy components suggests that the dispersion interaction is very important, at least for some of the geometrical configurations of the RDX dimer and, therefore, methods that are unable to properly account for the dispersion interaction (such as the supermolecular DFT method with standard density functionals) cannot be expected to yield correct results. With the full potential energy surface of the RDX dimer which is under development, we are able to model the properties of this important energetic material