HCN: Hydrogen‐Bonded Versus Conjugated Polymer

Abstract

AbstractResults of a density‐functional study of linear HCN and CNH monomers, the corresponding hydrogen‐bonded polymers, and a conjugated polymer (CHN)x with C and N atoms alternating along a zigzag chain are reported. Minimizing the total energy as a function of structure results in realistic structures for the monomers and the conjugated polymer; but the local‐density approximation may be responsible for the too short hydrogen bonds found for the hydrogen‐bonded polymers. For the optimized structures we present electronic energies, densities of states, photoelectron spectra, momentum densities, and reciprocal form factors. Comparing these clearly demonstrates both similarities and differences for the various systems. It is further demonstrated that the conjugated polymer can lower the total energy upon a C–N bond‐length alternation. A model is then constructed with which solitons and polarons in the conjugated polymer are examined. Both types of structural defects are stable for the charged chains and induce two gap‐states. Finally, polarons in the hydrogen‐bonded chains are discussed.