Sudden polarization in interacting model π systems: an exact study

Ramasesha, S. ; Albert, I. D. L. (1990) Sudden polarization in interacting model π systems: an exact study Chemical Physics, 142 (3). pp. 395-402. ISSN 0301-0104

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The twisted excited state of polyenes has attracted much theoretical and experimental attention due to the postulate that it exhibits sudden polarization for twist angle θ=90°. We examine this phenomenon in long chain polyenes using correlated model Hamiltonians. While the Hubbard model is employed to study this process as the correlations are gradually turned on, the Pariser-Parr-Pople (PPP) Hamiltonian is employed for a realistic study of long chain polyenes. Exact polarizabilities of the ground and excited states of polyenes with upto ten carbon atoms are calculated within the Hubbard and PPP models as a function of twist angle. We find that the dipole allowed excited states exhibit sudden polarization in all the cases. Besides, the 3 1Ag state in the covalent subspace which is a two-photon state also exhibits this phenomenon as it becomes degenerate with the dipole allowed excited state. It is suggested that photochemical processes involving zwitterionic intermediates should be possible through two-photon excitation to this covalent excited state.

Item Type:Article
Source:Copyright of this article belongs to Elsevier Science.
ID Code:39494
Deposited On:13 May 2011 09:06
Last Modified:13 May 2011 09:06

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