Why is this reactive force field file invalid format?

Dear all,

Invalid force field file format" in LAMMPS.

Thank you for your help in advance.

Best regards,


When I use a small test input:

units real
atom_style charge
region box block -5 5 -5 5 -5 5
create_box 1 box
pair_style reaxff NULL
pair_coeff * * ffield.reaxff.CrOFeSCH Cr

I get the following error message:

ERROR on proc 0: ffield.reaxff.CrOFeSCH:71: Invalid force field file format (src/REAXFF/reaxff_ffield.cpp:584)

Which means the invalid format is in line 71 of the file.

That line reads:

     10.0000   2.5000   4.0000   0.0000   0.0000   5.00009999.9999   0.0000     

Which is causing the issue due to joining two columns (5.000 and 9999.9999). That would work with a Fortran program using an explicit format, but breaks the force field reader in a C/C++ code like LAMMPS. You can easily fix this issue by changing the problematic line to something like this:

     10.0000   2.5000   4.0000   0.0000   0.0000   5.0000 9999.999   0.0000     

This is part of an entry for an element X that is bogus anyway.

Great! This is indeed the problem, thank you!