Pair_style hybrid between reax/c and lj

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1

Dear Lammps’ Users,

I am trying to simulate a molecular system using Reax FF (reax/c). In the meantime, I would like to add some additional “particles” which interact with each other by LJ. I searched the online documents and found the pair_style hybrid. Can anyone give any suggestion on the input command?

FYI, I have seven-atom types which are C H N O S Al Si. C H N O S use reax/c. Al and Si follow LJ. Should I use some input command as follow? Also, do I need to change control file?

pair_style hybrid lj/cut 12.0 reax/c control.reax_c.rdx
pair_coeff * * reax/c ffield.reax C H N O S NULL NULL
pair_coeff 1 6 lj/cut 1.0 1.0
pair_coeff 2 6 lj/cut 1.0 1.0

pair_coeff 3 6 lj/cut 1.0 1.0
pair_coeff 4 6 lj/cut 1.0 1.0

pair_coeff 5 6 lj/cut 1.0 1.0
pair_coeff 6 6 lj/cut 1.0 1.0

pair_coeff 7 6 lj/cut 1.0 1.0
pair_coeff 1 7 lj/cut 1.0 1.0

pair_coeff 2 7 lj/cut 1.0 1.0
pair_coeff 3 7 lj/cut 1.0 1.0

pair_coeff 4 7 lj/cut 1.0 1.0
pair_coeff 5 7 lj/cut 1.0 1.0

pair_coeff 7 7 lj/cut 1.0 1.0

I would really appreciate your help on the input script. Thanks in advance.
Regards,
Shuai

2

Dear Lammps' Users,

I am trying to simulate a molecular system using Reax FF (reax/c). In the
meantime, I would like to add some additional "particles" which interact
with each other by LJ. I searched the online documents and found the
pair_style hybrid. Can anyone give any suggestion on the input command?

​there have been numerous discussions on the value and shortcomings of
using pair style hybrid with ReaxFF on this very mailing list in the past.
technically, it is possible, but there are conceptual issues. whether they
apply for your specific case is your decision.​

FYI, I have seven-atom types which are C H N O S Al Si. C H N O S
use reax/c. Al and Si follow LJ. Should I use some input command as follow?

​syntactically, it looks correct, but you can test that better yourself by
just running it. however, the epsilon and sigma values look very wrong to
atomic scale systems with real units.​

​axel.​