Permanent Bonds in Reax/c


I would like to accelerate some reactions in a system by using parallel tempering later on. However, I would like to weed out any undesirable products that form as a result of using high temperature in the simulation box. Therefore, I am now considering some different methods to keep the non-reacting bonds fixed.

After reviewing the documentation, I believe fix restrain may suit my needs, but I have a question:

Can I use “special_bonds lj/coul” to turn off the pair-wise interaction between two bonded atoms? I can use “fix restrain bond” to define that the bond is there with some coefficient for stretching. Can special_bonds turn off the pair interaction between the atoms that are restrained? Will this effect the three body and four body interactions as well in ReaxFF since they are still considered “nonbonded”?

Thanks a lot!
Josh Deetz
PhD Candidate Student
Chemical Engineering
University of California, Davis

Special_bonds does not affect fix restrain. Pair reax also
does not pay attention to special_bonds at all, e.g.
by applying weighting factors. The only affect
is that if special_bonds are defined, then the neighbor list
passed to pair reax (or any other pair style) may be missing
some interactions (e.g. two atoms bonded to each other
will not be in the neighbor list if their wt factor is 0.0). This
is typically not what you want for ReaxFF. Fix restrain does
not use a neighbor list, so again the special_bond settings
have no affect on it.