Molecular Dynamics Simulations of Polyacetylene

Abstract

Molecular dynamics simulation methods have been used to study trans-polyacetylene both in its pristine and in its doped form. No constraints have been included in the simulations, so that both bond-lengths and bond-angles have been allowed to change. Bond energies, vibrational and structural data have been used to derive the potential parameters. The power spectra of the pristine polymer have been evaluated and they reproduce the main peaks observed in Raman and infrared experimental measurements. Doping by both lithium and potassium has been investigated at three different dopant levels. The results show that the mobility of the ions is remarkably high if their concentration is low. As the dopant level increases the displacements around the equilibrium positions become smaller and the dopants form an increasingly crystalline sublattice.

Key Words:

• Polyacetylene
• molecular dynamics