Computational Chemistry and Molecular Modeling
Atomic, Molecular and Optical Physics
Wiley InterScience Backfile Collection 1832-2000
Chemistry and Pharmacology
In the framework of the SCF-RPA scheme and ppp approximation we studied the excitation spectrum of pyrene, coronene, ovalene, and hexabenzocoronene. The triplet stability matrix of the corresponding Hartree-Fock solution was also studied for each molecule. At variance with the case of long linear polyacenes [M. Baldo, G. Piccitto, R. Pucci, and P. Tomasello, Phys. Lett. 95A, 201 (1983)], all these molecules do not display Hartree-Fock triplet instability. Furthermore, the theoretical analysis indicates that the electronic structure of the molecular series can be characterized by a dimensionality intermediate between one and two, with a smooth transition between the two limits. The transition is essentially determined by the molecular shape. The analysis is supported by the fairly good agreement of the theoretical spectra with the available experimental data.
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