The bond-order matrix &I the PPP model of alternant hydrocarbons is expressed in terms of.independe& parameters.and,.hence, the SCF energy itself is explicitly obtained in terms of these parameters. Direct minimization.of the ene&-y expression gives, besides those normally obtaikd, some new minima w
Convergence difficulties in the hartree-fock procedure for the PPP model of alternant hydrocarbons
✍ Scribed by Vlasta Bonačiá; Jaroslav Koutecký
- Publisher
- John Wiley and Sons
- Year
- 2009
- Tongue
- English
- Weight
- 238 KB
- Volume
- 5
- Category
- Article
- ISSN
- 0020-7608
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## Abstract Simple rules for an estimate of the correlation effects in the low‐lying states of alternant hydrocarbons, as described by the Pariser–Parr–Pople Hamiltonian, are formulated. These rules are based on the alternancy and spin symmetry classification of states in both strongly and weakly c