You will have to be more specific about “what” does not work. You also need to specify the version of LAMMPS you are using. Note that ReaxFF is a pure atomic potential meaning that there is no pre-defined bonds, angles, dihedrals and impropers. This means your data file is not right. You will also need to check the Lit. to verify that the particular CHO force field you are using is properly trained for PE oxide.