Temperature drops to zero in NVT with ReaxFF

I met this issue recently: Temperature drops to zero in NVT with ReaxFF.
If you happened to meet this problem too, the following tips you can try with:

(1) Always check the UNITs you used first.

(2) Try a shorter timestep, since the timestep in ReaxFF is normally 5-10 times shorter than the one you used in MD with other force functions.

(3) After relaxation of system (such as NPT), don't create the velocity again before next step (such as NVT). Since ReaxFF is very sensitive to the neighbor environment, if new velocity is introduced, its neighbor environment could be dramatically changed.

(4) While relaxing the system box with NPT, try to make the size of box change slowly. Dramatic change of box size will change the neighbor environment.

(5) In my case, the steps of my calculation is:  Create velocity at low temperature => Relax system with NPT => Create velocity with a higher temperature  => NVT => NVE.
    * If I skipped the NVT step,  the NVE step can run well.
    * If I skipped the Step of Creating a new velocity, the NVT step can run well.