problem encountered when using the Reaxff potential.

Please post future queries to the LAMMPS mailing list.

Your question is not about the code, but about the particular Ti/O ReaxFF parameterization. The ffield.reax file you are using is not part of the LAMMPS distribution, so it is impossible for me to say if it is correct or not. Looking at the movie, I have to assume it is completely wrong, because the oxygen molecules appear to be moving straight through the Ti atoms.

Before you attempt to run your application, you should first verify that you can reproduce the results published in the paper where the Ti/O potential was presented. If not, contact the authors for help.