Degenerate -sigmatropic rearrangement of propylene

This reaction will be analysed in somewhat greater detail than has been done up to now. As noted in Section 7.1.1.1, a common assumption made whenever reaction path computations are carried out is that the same atomic orbital basis set is adequate for following the reaction path. If the reactive system is made up entirely of carbon and hydrogen atoms, the electron and orbital count is particularly simple Each C atom brings four electrons and each H atom provides one the minimal basis set comprises a I5 AO for each H atom and a set of four - one 2s and three 2p AOs - for each C atom. The number of independent linear combinations that can be constructed from a system with Nc carbon and A h hydrogen atoms is therefore iNc + iVu), half of which will be occupied and half unoccupied in the closed shell ground-state of all the molecular species concerned. 

Orbitals in minimal basis set 18 Valence electrons 18 Symmetry species of the atomic and group orbitals in 02  

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