Rare gas bond property of Rg-Be2O2 and Rg-Be2O2-Rg (Rg = He, Ne, Ar, Kr and Xe) as a comparison with Rg-BeO

► The electron correlation effect is significant for Rg-Be2O2. ► Rg-Be2O2 rare gas bond is more van der Waals nature than that of Rg-BeO. ► For He-BeO, the back-donation from O to Be would contribute to the stability of the binding.