Polyynes linear infinite

The prototype of a conjugated polymer is the linear, infinite chain of carbon atoms. For a recent survey of experimental work on polyynes, often also termed carbynes, see (4). Only a few ab initio calculations have been performed on polyynes in the past (5-7). Here we present data considerably improved with respect to lattice summations than the previously published calculations. 

Karpfen A., Ab Initio Studies on Polymers I The Linear Infinite Polyyne, J.Phys. C12 (1979) 3227-3237. 

Kirtman et al.149 show how low frequency collective modes contribute to the dynamic vibrational hyperpolarizabilities of different linear chains (polyacetylene, polyyne, polyethylene and polysilane). In another work Champagne et al.150 have calculated the static vibrational yvL/N of polyacetylene and they have found it to be 30% larger than the electronic contribution, while in the case of polyyne yj[/yL is 0.92151 at the extrapolated infinite chain length. For polydiacetylene and polybutatriene both the static electronic and the vibrational contributions to a /N and ctvL/N, and yl/N and yj JN, respectively, were computed. Also in these cases for both chains the vibrational contributions are of the same order as the electronic ones. One should mention, however, that in these cases the yL/N values extrapolated to infinity are about 10% larger than the values obtained for seven or ten units, respectively, in the two chains. Finally for d -trans polysilane154 the static y /N and yvL/N and values were also calculated. Their values have been found also to be of comparable magnitude. 

An intriguing aspect of carbon chemistry is the preparation of infinite one-dimensional rods constituted of alkyne units. Interest in such compounds dates back to Baeyer, who studied the oxidative Glaser [66] coupling of acetylenes in the search for infinite linear chains of pure carbon [67]. A century later, the preparation and characterization of infinite linear polyynes [-(CsQ -] named carbynes were actively pursued using a variety of methods [68], But reports of the preparation and structure of these materials, which are calculated to be onedimensional conductors, remain controversial [69]. 

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