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Multiply Charged Ions

Multiply Charged Ions. Quantum Chemical Computations Trento, May 2002 Lecture 4. Multiply Charged Ions. AB ++ Minima. Single-reference Methods Sometimes, Multi-configuration nature Geometry Energetics Properties E.g. Fe ++ (Benzene) 2 (M. Kaczorowska). Example. TiF 2,3+

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Multiply Charged Ions

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  1. Multiply Charged Ions Quantum Chemical Computations Trento, May 2002 Lecture 4

  2. Multiply Charged Ions

  3. AB++ Minima • Single-reference Methods • Sometimes, Multi-configuration nature • Geometry • Energetics • Properties • E.g. Fe++(Benzene)2 (M. Kaczorowska)

  4. Example TiF2,3+ Schroder, Harvey, Schwarz CCSD(T)

  5. Excited States • Except where Spin, symmetry different: • Multi-configuration nature • MCSCF / MR-CISD • Energetics

  6. Avoided Crossing • Very weak avoided crossing • Highly non-adiabatic behaviour • Poor convergence even with MCSCF • (TiF3+) • Semi-empirical treatment: Reaction window model + Landau-Zeener

  7. Adiabatic Barriers • Zr++ / CH4 (M. Kaczorowska) Schroder, Harvey, Schwarz, JPC A, 2000, p. 11257

  8. Potential Energy Surfaces

  9. Dications

  10. Simple Example

  11. Anions and Dianions

  12. Conclusions • Calculations are easy! (Especially if quantitative answers are not needed) • One can reliably predict the structure, properties, and energetics of ground state molecules and ions • Dications, dianions, excited states can be a bit more difficult, and reactivity also • Hardware is not expensive! • Great expertise is not needed (but lots available within Network – Jan, …) • I am available for informal advice (choice of level to apply, …) and help

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