Polycarbonitrile: a Dft Investigation of Structural Stability

INTRODUCTION The fact that polyacetylene (PA) [C2H2]∞ is isoelectronic with polycarbonitrile (PCN) [CHNH]∞ has caused many theoretical studies to investigate the later compound in diverse levels of theories, but using a fully trans structure [1], since this is the most stable structure for PA. More recent studies of the structural and thermodynamic stability using PCN in fully trans, cis-transoidal, and trans-cisoidal configurations have indicated that the cis-transoidal structure is more stable than a fully trans [2] showing that the use of the fully trans configuration of the PCN can generate errors, as for example the study polarizability and hyperpolarizability of this polymer [3]. In this work the structural stability of polyacetylene with different number of monomeric units was evaluated by substituting carbon atoms by nitrogen, but maintaining nitrogens always separated by at least one carbon atom.