  The Kremer-Grest (KG) model is a standard for studying generic polymer
properties. Here we have equilibrated KG melts up to and beyond $200$
entanglements per chain for varying chain stiffness. We present methods for
estimating the Kuhn length corrected for incompressibility effects, for
estimating the entanglement length corrected for chain stiffness, for
estimating bead frictions and Kuhn times taking into account entanglement
effects. These are the key parameters for enabling quantitative, accurate, and
parameter free comparisons between theory, experiment and simulations of KG
polymer models with varying stiffness. We demonstrate this for the mean-square
monomer displacements in moderately to highly entangled melts as well as for
the shear relaxation modulus for unentangled melts, which are found to be in
excellent agreement with the predictions from standard theories of polymer
dynamics.
