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1 Department of Physics, Chemistry and Pharmacy, Faculty of Science, SDU 2 unknown 3 Kemisk Institut, Faculty of Science, SDU 4 Department of Physics, Chemistry and Pharmacy, Faculty of Science, SDU 5 Kemisk Institut, Faculty of Science, SDU
An alternative separation of short-range exchange and correlation energies is used in the framework of second-order range-separated density-functional perturbation theory. This alternative separation was initially proposed by Toulouse and relies on a long-range-interacting wave function instead of the noninteracting Kohn-Sham one. When second-order corrections to the density are neglected, the energy expression reduces to a range-separated double-hybrid (RSDH) type of functional, RSDHf, where "f" stands for "full-range integrals" as the regular full-range interaction appears explicitly in the energy expression when expanded in perturbation theory. In contrast to the usual RSDH functionals, RSDHf describes the coupling between long- and short-range correlations as an orbital-dependent contribution. Calculations on the first four noble-gas dimers show that this coupling has a significant effect on the potential energy curves in the equilibrium region, improving the accuracy of binding energies and equilibrium bond distances when second-order perturbation theory is appropriate. © 2013 American Physical Society.
Physical Review a (atomic, Molecular and Optical Physics), 2013, Vol 88, Issue 2
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