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 respec ts. In the present work a united atom potential incorporating an offse t 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 u sed as the criteria for accomplishing this. It is found that good agre ement between experiment and molecular dynamics simulation for these q uantities can be achieved. Some aspects of the atomistic details of pa cking are discussed and the onset of vitrification in V-T curves is ex amined.