  The widely used double-bridging hybrid (DBH) method for equilibrating
simulated entangled polymer melts [R. Auhl et al., J. Chem. Phys. v. 119, p.
12718, 2003] loses its effectiveness as chain stiffness increases into the
semiflexible regime because the energy barriers associated with double-bridging
Monte Carlo moves become prohibitively high. Here we overcome this issue by
combining DBH with the use of core-softened pair potentials. This reduces the
energy barriers substantially, allowing us to equilibrate melts with $N \simeq
40 N_e$ and chain stiffnesses all the way up to the isotropic-nematic
transition using simulations of no more than 100 million timesteps. For
semiflexible chains, our method is several times faster than standard DBH; we
exploit this speedup to develop improved expressions for Kremer-Grest melts'
chain-stiffness-dependent Kuhn length $\ell_K$ and entanglement length $N_e$.
