Effect of nanosizing on some properties of one-dimensional polyacetylene chains

Density functional theory at the B3LYP/6-31G* level is used to calculate equilibrium geometry of the one-dimensional trans polyacetylene chains (C2H2)n from n=2 to 20 which are of nanometer length. The Raman frequencies, intensities, optical absorption , oscillator strength, ionization potential, electron affinity and binding energy per monomer are calculated as a function of the chain length in the nanometer range. The results show with the exception of the oscillator strength of the absorption that there is a small critical length less than 4 nm at which changes of properties become significant and this length is property dependent.