Unable to find reax parameter

Hello,

I am trying to find all parameters involved in the Valence angle energy equation in ffield.reax.cho. I am using the supplemental information from the manuscript:

https://pubs.acs.org/doi/suppl/10.1021/jp709896w/suppl_file/jp709896w-file002.pdf

and

https://pubs.acs.org/doi/suppl/10.1021/jp709896w/suppl_file/jp709896w-file004.pdf

which show the ffield file and the functional forms of the energy terms, respectively. I am having trouble finding the parameter “p_{val6}” in equation 13c. This parameter is not identified ffield.reax.cho in the LAMMPS package, or in the corresponding ffield file in supplemental information for the paper. I am also having trouble finding it in “reaxc_ffield.cpp” (3Mar20), where the force field parameters are read into memory in LAMMPS. Has the name of this parameter been changed?

Thanks and best regards,

-Keith

CCing Aidan and Metin who may be able to help.

Steve

Sorry about the slow response.

p_val6 (along with other valence angle related parameters) are still there in the reaxc_valence_angles.cpp file.

image001.png

Here is the direct link for your convenience: https://github.com/lammps/lammps/blob/7d46aa6185051c2d193d0d53a648f0d19d34d1ae/src/USER-REAXC/reaxc_valence_angles.cpp#L119

This means p_val6 is part of the global parameters block, and it is the 14th among them (with 0-based indexing).

I think the issue is that they have marked it as p_val7 in the SI file of their manuscript for some reason. I double checked and the global parameters block (which this parameter belongs to) in newer force field fields gives more explanatory remarks rather than giving the parameter name.

Hope this helps!

Metin

​Much appreciated prof Aktulga.

Thanks and best regards,

-Keith

image001.png