Simulations of infinite nuclear matter at different densities, isospin asymmetries and temperatures are per-formed using the isospin-dependent quantum molecular dynamics (IQMD) model to study the equation of state and symmetry energy. A rigorous periodic boundary condition is used in the simulations. Symmetry energies are extracted from the binding energies under different conditions and compared to the classical molecular dynamics (CMD) model using the same method. The results show that both models can reproduce the experimental results for the symmetry energies at low densities, but IQMD is more appropriate than CMD for nuclear matter above the satu-ration density. This indicates that IQMD may be a reliable model for the study of the properties of infinite nuclear matter.