Pair style ZrH2

My name is Ravi.I would like to look at Zirconium Hydride ZrH2.I have two different potentials Zrncs500.eam and hmib.eam.I used LAMMPS and run the program using the following pair coefficient command.

pair_style eam
pair_coeff 1 1 Zrncs500.eam

pair_coeff 2 2 hmib.eam

My structure(hcp) is stable for shoter timeperiods i.e for 900000.when I run it for 7000000 iterations the structure is becoming unsable.Could anyone tell me whether I am using correct pair coefficient command and also any suggestion on timesteps.

Thanks for Help

If you can run for 1M steps, you are
certainly using the pair_style command correctly.

To check the timestep, you need to run tests with
different size steps and see how you conserve energy.

You should also realize that with your 2-type system, the
eam pair style will "mix" the 2 EAM potentials you
list to calculate the cross-interactions. As described
on the EAM doc page. Whether that results in a good
model for your alloy system is up to you to figure out.
There is no guarantee that it does. Many people derive
eam/alloy potentials that explicitly include a fitted alloy
term, instead of letting it be auto-mixed.