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Multiply Charged Ions

Multiply Charged Ions. Quantum Chemical Computations Trento, May 2002 Lecture 3. Multi-Reference Methods. Unrestricted Hartree-Fock. Multi-Configuration Self-Consistent Field (MCSCF). Bond Dissociation Multi-configuration nature E.g. O 3 TiF 3+ ( 1  + ). MR-CI(SD).

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Multiply Charged Ions

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  1. Multiply Charged Ions Quantum Chemical Computations Trento, May 2002 Lecture 3

  2. Multi-Reference Methods

  3. Unrestricted Hartree-Fock

  4. Multi-Configuration Self-Consistent Field (MCSCF) • Bond Dissociation • Multi-configuration nature • E.g. O3 • TiF3+ (1+)

  5. MR-CI(SD) • Only MR-CISD practical • Size inconsistent (“Davidson correction”) • MR-ACPF, MR-AQCC • CASPT2, MR-MBPT, CASMP2

  6. Excited States • CIS, TD-DFT, CCSD-EOM • MC-SCF • (Spin, symmetry)

  7. He22+ – avoided crossing

  8. Density Functional Theory Hohenberg & Kohm: E = E() E = VNN + T() + VNe() + Vee() Kohn-Sham:  = i2

  9. DFT – 2 E() = VNN + TS() + VNe() + J()+EXC() EXC() not known LDA, BP86, BLYP, GGA (PW91), B3LYP

  10. Relativity • Scalar Effects • Spin-orbit Coupling

  11. Accuracy • HF: good geometries • MP2: good geometry, energy when appropriate • DFT: good geom + energy • CCSD(T) / MR-CISD: excellent energetics where applicable

  12. Expense • HF: N4 • MP2: N5 • DFT: N3 • CCSD(T): N7 • MCSCF, MR-CISD: eN • Efficient codes for HF, MP2, DFT, CCSD(T)

  13. Programs Gaussian (98) - John Pople ACES II (R. J. Bartlett, Floride - CC methods) ADF (Amsterdam, DFT) CADPAC (Cambridge, U.K.) Columbus (I. Shavitt, Columbus, Ohio) Dalton (Norway) Gamess-USA (M. Gordon, M. Schmidt, Iowa) Gamess-UK (Daresbury, UK) Jaguar (Schrödinger, inc - R. Friesner, Portland, Oregon) MOLCAS (Lund, Suède, B. Roos) MOLPRO (P. Knowles / H.-J. Werner, UK/Allemagne) NWChem (PNL, USA) Q-Chem (Gill, Head-Gordon, Schaeffer, …) Spartan (W. Hehre, Wavefunction inc.) Turbomole (R. Ahlrichs)

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