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Unformatted text preview: 10.675 LECTURE 13 RICK RAJTER 1. Today → project description and literature search CI revisited → → partial CI, CID, CISD, MP → Coupled-Cluster, CCD, CCSD, QCISD → G1, G2, G3 and comparisons 2. Concepts CI Size Consistent → → Variationality 3. CI vs DFT Extremely expensive and can only take into account a few atoms DFT: Cost of a HF, but includes correlation However, DFT has no systematic way of getting more accurate with computation resources. Meaning, there is no way to know if we are more or less accurate. CI, recall that with a large enough basis set, gives the exact, non-relativistic energies. C r Ψ r C rs Ψ rs Φ o = C o Ψ o + ar a o + + a<b,r<s ab ab Ψ → Hartree-Fock determinants ”single excitations” of HF determinants. CI size consistent variational (method is equally accurate for systems with → different number of electrons. DFT/HF also has these properties 4. CI Problems Scales wtih N!, where N is the # of basis sets. Partial CI terminates the full CI series CID → configuration interaction doublets C rs Ψ rs Φ CID = Φ o...
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- Spring '03
- Quantum Chemistry, Trigraph, Basis set, zero-point energy, Coupled cluster, EC ID