Intermolecular dispersion energies from time-dependent density functional theory.
Non-expanded dispersion energies are calcd. from time-dependent coupled-perturbed d. functional theory (DFT) employing various non-hybrid and hybrid exchange-correlation potentials and suitable adiabatic local d. approxns. for the exchange-correlation kernel. Considering the dimer systems He2, Ne2, Ar2, NeAr, NeHF, ArHF, (H2)2, (HF)2, and (H2O)2 the effects of intramonomer electron correlation on the dispersion energy are accurately reproduced with the PBE0AC exchange-correlation potential. In contrast, the uncoupled sum-over-states approxn. yields unacceptable errors. These are mainly due to neglect of the Coulomb and exchange-correlation kernels and therefore, not substantially improved through an asymptotic correction of the exchange-correlation potential.
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