Rapid estimation of the electronic correlation energies for van der Waals complexes Original Research Article

We present the rules of calculations of pair electron correlation energies for Rg(Ne, He), X (X=F, Cl, Br) and the corresponding van der Waals complexes RgX at MP2/6-311++G(d) level and He, Ne, HeF and NeF with larger cc-PV5Z* basis set using ROHF-OPT2 method of meld program. The analyses from the aspects of pair correlation energies, charge distributions and orbital coefficients indicate that the correlation effects between Rg and atom X in the RgX systems are very small. Comparing the results of electron correlation energies between RgX and Rg+X, we propose a rapid approximation estimation method to estimate the correlation energies for van der Waals complexes by directly summarizing the correlation energies of Rg and X systems.