Questions tagged [many-body-perturbation-theory]

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How should I compare different basis sets for post-Hartree-Fock methods?

HF or DFT methods are variational so I can confidently say that any basis set that gives the lowest energy is the best for that system. However, I have learnt that post-HF methods such as MP2, MP3, ...
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0answers
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Why are single excitations ignored in the MP2 component of double hybrid functional calculations?

In the original paper by Grimme introducing double hybrid functionals (also summarized in just 3 paragraphs here), it says: "[As] opposed to nonempirical versions of KS-PT2 [19], the single ...