Potential energy calculations on polyacetylene

Potential energy calcns. on the isolated chains of polyacetylene [25067-58-7] were made as a function of the no. of rotational degrees of freedom allowed to the chain, of the barrier height to bond rotation, of the cis and trans configuration, of the mol. geometry, and of the Van der Waals potential functions. The data support the view of a conformation slightly distorted from planarity for the trans polymer, with possible conformational disorder within the chain, and of a "diln. effect" of cisoidal units within trans sequences for the trans-cisoidal conformation. For the cis polymer a "gauche" conformation is likely the most stable one, with alignment of the double bonds belonging to succeeding helical turns whose distance is 3.3 Å giving rise to π-π intramol. interactions