  Molecular dynamics simulations were conducted to investigate the structural
properties of melts of nonconcatenated ring polymers and compared to melts of
linear polymers. The longest rings were composed of N=1600 monomers per chain
which corresponds to roughly 57 entanglement lengths for comparable linear
polymers. For the rings, the radius of gyration squared was found to scale as N
to the 4/5 power for an intermediate regime and N to the 2/3 power for the
larger rings indicating an overall conformation of a crumpled globule. However,
almost all beads of the rings are "surface beads" interacting with beads of
other rings, a result also in agreement with a primitive path analysis
performed in the following paper (DOI: 10.1063/1.3587138). Details of the
internal conformational properties of the ring and linear polymers as well as
their packing are analyzed and compared to current theoretical models.
