08-CompChem7-1 - Electron Correlations: post-HF (Correlated...

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Electron Correlations: post-HF (Correlated ab initio MO) methods and Density Functional Theory (DFT) methods Lecture 7 08.3.25 CH418 Computational Chemistry KAIST
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[2-4] . Post HF Methods ; Electron Correlation Methods. (2-4-1) L * . E corr = E non-rel,true - E HF : Difference between the exact non-relativistic energy and the Hartree-Fock limit energy. Static correlation : near-degeneracy effects, internal correlation : Improper description of a state by a single determinant wave function. --> Demands multi-reference determinants. cf. MCSCF and CASSCF. Dynamic correlation : from the two-electron cusp. -- Improper description for short distance multi-electron coordinates. (about 20 kcal per e pair) Multi-particle basis expansion. = Ψ Ψ = Ψ i i i i C . ts Determinan Slater :
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General Approaches • include r 12 in the wavefunction suitable for very small systems too many difficult integrals Hylleras wavefunction for helium expand the wavefunction in a more convenient set of
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This note was uploaded on 06/28/2011 for the course CHEM 6440 taught by Professor Yoonsuplee during the Spring '11 term at Korea Advanced Institute of Science and Technology.

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08-CompChem7-1 - Electron Correlations: post-HF (Correlated...

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