We study liquid diphenyl carbonate (DPC) with molecular dynamics simulations in the temperature range from 350 to 600 K. The diffusion behavior as well as structural and relaxation properties of this complex liquid are analyzed in detail. To this end, an all-atom force field is developed for DPC. We studied two sets of partial charges and the influence of the torsion barrier at the carbonate group. We discuss radial distribution functions, orientation distribution functions, and orientation correlation functions of subgroups of the molecule. The flip frequencies of the dihedral angles of the phenyl rings and of the carbonate group are also considered. The internal flexibility and the nonspherical form of the molecule highly improve the diffusion process, whereas the height of the carbonate group torsion barrier,is not a crucial parameter.