An all-atom CFF93 force field for polycarbonates based on ab initio calculations is reported. Force field parameters are derived by fitting to quantum mechanical total energies, first and second derivatives of total energies, and electrostatic potentials, all generated from ah initio quantum mechanical calculations on model compounds at HF/6-3 1G* level of theory. Valence parameters and ab initio charges are then scaled to correct for differences between experiment and the Hartree-Fock approximation. The van der Waals parameters and the scaling factors for atomic partial charges are determined from crystal structures. Based on the force field, molecular mechanics calculations are performed for several model compounds, and the results are compared with experimental values and with the results of the ab initio calculations.