The static dipole polarizability and second hyperpolarizability tensors are calculated for polyene systems via ab initio coupled‐perturbed Hartree–Fock theory. The effect of basis set augmentation on the calculated properties is explored for C4H6 and example basis sets are used to calculate the polarizability and second hyperpolarizability for the longer polyenes: C6H8, C8H10, C10H12, C12H14, C14H16,C16H18, C18H20, C20H22, C22H24. Results for the finite polyenes are extrapolated to predict the unit‐cell polarizability and second hyperpolarizability of infinite polyacetylene. The working equations which take advantage of the 2n+1 theorem of perturbation theory for calculating up to the second hyperpolarizability are given, and their implementation is briefly discussed. In particular it is shown that the implementation is readily amenable to parallel processing.

Ab initio analytic polarizability, first and second hyperpolarizabilities of large conjugated organic molecules: Applications to polyenes C4H6 to C22H24

Poly(1,6-heptadiyne)-Based Materials by Metathesis Polymerization.

https://pure.tue.nl/ws/files/1422993/587897.pdf

Synthesis, processing and material properties of conjugated polymers

Some of the current directions in research on new organic materials
based on functionalized oligoarylenes are reviewed. Particular emphasis is
placed upon the use of chemical synthesis for the incorporation of suitable
functionalized oligoarylenes into more complex molecular and polymeric systems.
Selected examples of applications of these materials in different fields such
as light-emitting diodes, photovoltaic devices, nonlinear optics, two-photon
dyes, molecular switches or ligands will be presented.

Functionalized oligoarylenes as building blocks for new organic materials

Diagrammatic valence‐bond (DVB) theory is extended to dynamic nonlinear susceptibilities of interacting π electrons in Pariser–Parr–Pople (PPP) or other quantum cell models whose correlated ground state ‖G〉 is known. Corrections φ(1)(ω) and φ(2)(ω2,ω1) to ‖G〉 due to oscillating electric fields are found directly as linear combinations of VB diagrams. Any nonlinear optical coefficient is reduced to matrix elements that implicitly include all excited states, as verified for shorter polyenes. Static and dynamic χ(3) coefficients for cis and trans polyenes to N=12 carbons illustrate the importance of retaining the full spectrum. The coefficients βijk(ω,ω) for second harmonic generation are found for polar molecules like aniline and nitroaniline. Divergent responses are treated by lifetimes Γ for the resonant states, as shown for third harmonic generation in hexatriene with Γ=0 and in octatetraene with Γ>0. Electron–electron interactions reverse the sign of γijkl(ω,ω,ω) in linear polyenes, except for the large...

Valence bond approach to exact nonlinear optical properties of conjugated systems

X(3) of trans-(CH)x: Experimental observation of 2Ag excited state

Frequency dependence of the large, electronic χ(3) in polyacetylene

Measurements of the first x (1) and the third order optical susceptibilities X (3) in the spectral region below the band edge of polyacetylene are reviewed. The absorption spectrum in trans-(CH) x has an intense peak due to the onset of the strong interband transition near 2 eV. Inside the semiconducting gap the absorption has an exponential band edge and the transmission losses are dominated by scattering effects. The magnitude of the electronic contribution to the X (3) parallel to the polymer chains in trans-(CH)x is in excess of 10-9 esu for wavelengths larger than 1.3 μ.m, and is one of the largest values for the electronic X(3) inside the gap of a semiconductor. The spectrum of X (3) in trans-(CH) x has a sharp two-photon resonance that has been attributed to the presence of the 21Ag excited state near band edge. It is suggested that through appropriate control of morphology, noncrystalline, processable conjugated polymers can be useful in optoelectronic applications.

Linear And Nonlinear Optical Properties Of Polyacetylene

Conjugated polymers possess a 1-D band structure; a property which when coupled to their large intrachain bandwidth allows extensive 1-D delocalization of the electronic wave function. The unique delocalization is predicted to give rise to extremely fast (<1 ps) and large electronic third-order optical susceptibilities [χ(3)]. χ(3) the measure of the change in the index of refraction with the pulse intensity and is the most important material parameter for use in an all-optical device. As the prototype conjugated polymer, polyacetylene provides a unique opportunity for studying the nonlinear optical response of this potentially useful class of optoelectronic materials.

J. Messier

Papers

X(3) of trans-(CH)x: Experimental observation of 2Ag excited state

Frequency dependence of the large, electronic χ(3) in polyacetylene

Linear And Nonlinear Optical Properties Of Polyacetylene

Frequency dependence of the large, electronic χ (3) in polyacetylene