A MOLECULAR-DYNAMICS SIMULATION OF POLYETHYLENE

There is recent evidence that united atom CH2 Lennard-Jones nonbonded potentials commonly used for molecular dynamics simulations for liquid polymers such as polyethylene are inadequate in some important respects. In the present work a united atom potential incorporating an offset of its center from the carbon atoms (the ''anisotropic united atom'' potential form suggested by Toxvaerd) is calibrated for polyethylene. Equation of state (PVT) and heat of vaporization representation are used as the criteria for accomplishing this. It is found that good agreement between experiment and molecular dynamics simulation for these quantities can be achieved. Some aspects of the atomistic details of packing are discussed and the onset of vitrification in V-T curves is examined.