All-atom simulations of isotactic polystyrene (PS) melts are performed in LAMMPS (Largescale Atomic/Molecular Massively Parallel Simulator). The OPLS (Optimized Potentials for Liquid Simulations) force field is employed to describe the potential energies of the system. The initial configuration prepared by AutoPoly (Wu/AutoPoly) consists of 50 chains, each with 10 monomers. Periodic boundary conditions are applied in the X, Y, and Z directions to simulate the bulk properties of PS melts. The equation of motion is integrated based on a velocity-verlot algorithm with a time step of 1 fs.