Thanks, those files are in the src directory. I had used the included example input scripts in.reax.rdx and in.reax.tatb, which I have not edited.
Comparing the scripts to the documented form of the command at
http://lammps.sandia.gov/doc/pair_reax.html
I added the second parameter hbnewflag = 0 to the files and ran without errors. It appears the provided input scripts are missing the 2d optional parameter and line 9 should read:
pair_style reax 10.0 0 1.0e-6
How do I submit these changes for inclusion?
Jane