VBTutorial2

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VB applications on PI systems

To the Tutors

Sason remarks and prospective 2 hours talk +

Philippe's remark on the initially proposed tutorial. are included in bold.

Qualitative

• Exercices from The Book ... >PCH< (30')

Computational

• Allyl cation : VB 3 configuration (3rd configuration has a large weight).
• Benzene : question about basis of covelent structures (paper exercise, then xmvb zith str=cov), then all ionics.
• Ozone : paper exercise ; expand MO wf in VB basis, wieghts of biradical with HF, compute with XMVB (VBSCF, BOVB)
• Benzyl radical with most spin alternant determinants (2 determinants) (p228 of The Book) show spin location. Objection : this uses Heisenberg spin hamiltonian theory, a topic that we do not teach.

(trash: * O2 paradigm : compute singlet - triplet gap : too hard

• H2O lone pairs : compute H2O+ states (2 configurations mixing) Objection : did you try to do that ? If we let the orbitals optimize themselves, I guess we will converge to the MO solution with weight 1.0, the other structure with weigt 0.0. The H2O+ states would better be done as qualitative exercises.)

Exercices

Exercice 1 : The allyl radical and cation

Subject

Here is a image example

Image example: Allyl Cation MO's

Th

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title title

Exercice 3 : Radical caracter of ozone

1. What is the complete basis of VB structure for the ozone molecule ?