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Articles you may be interested in πelectron polarizabilities of infinite organic polymers J. Chem. Phys. 97, 9389 (1992); 10.1063/1.463315Ultraviolet photoemission study of oligothiophenes: The effect of irregularity on πelectron systems A screened potential molecularorbital calculation of the πelectron systems of metalloporphin, metallochlorin, and metallobacteriochlorin A screened potential molecularorbital calculation of the πelectron system of porphyrin Finite-field technique has been applied to the calculation of 1T molecular polarizabilities within the P~~ser-Parr-Pople Hamiltonian. This formalism allows to analyze large oligomers contammg up to 400 atoms, and asymptotic behaviors may be attained in some cases. We have investigated the role of the polymer size, the backbone geometries, the presence of neutral and charged defects (solitons, polarons, bipolarons), the chemical nature of the monomeric unit on the polarizabilities. Generally, the polarizabilities are not deeply modified by a change of the geometrical characteristics, and may lead to huge values for sufficiently large chains. Besides, the charge of the system is the leading factor which determines the values of this property. The evolution of the polarizability with the number N of 1T atomic centers, au depends largely on the charge, and on the defect. For the neutral systems, the polarizability per monomeric unit au increases smoothly, and then exhibits an asymptotic behavior with N. For polymers with a defect, this variation is different: au first increases with N, reaches a maximum a for N and finally tends to an asymptotic value. The values of a umax for N max depend onuili~ type of ax , defect (soliton vs polaron) and are rather sensitive to the dependence of the first-neighbor oneelectron interaction with the interatomic distance. A large number of results on polyacetylene and poly heterocycles shows that there exists a simple law between the polarizability and the electronic gap, independently of the type of the monomeric unit. But this relation shows a deviation from a simple proportionality behavior, as soon as a reaches large values (as for example in polymers with defects).

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