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Instabilities of the symmetry-adapted restricted-hartree–fock ground state in infinite polyenes. I. Singlet instabilities

✍ Scribed by P. Karadakov; O. Castan̄o

Publisher
John Wiley and Sons
Year
1982
Tongue
English
Weight
701 KB
Volume
22
Category
Article
ISSN
0020-7608

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✦ Synopsis

Abstract

The singlet instabilities of the RHF ground state in infinite polyenes have been studied in the framework of a semiempirical PPP Hamiltonian, accounting for long‐range Coulomb interactions until convergence of the ground‐state energy per electron value. The symmetry‐adapted RHF solution (SAS) has been shown to be unstable to the formation of bond‐order alternation waves (BAW's) and charge‐density waves (CDW's). The CDW solutions have been shown to be higher in energy than the corresponding BAW solutions and to represent saddle points of the energy hypersurface, unstable to the formation of BAW's for physically realistic range of variation of the semiempirical parameters. Analytical formulas for the SAS ground‐state energy per electron have been derived in case of a Coulomb law and a Mataga–Nishimoto formula for the two‐center Coulomb integrals.

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