Pair_style reax/c NULL

LAMMPS LAMMPS Development
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1

When I use reax/c potential with setting “pair_style reax/c NULL”, there will always be one error reported appearing as “Pair reax/c requires use of fix qeq/reax or qeq/shielded”. In other words, I can’t use the command “pair_style reax/c NULL”.
Could you please help me, thank you.

2

There is simply not enough information here to diagnose this issue. You need to provide a more detailed description of the steps you did and the entire error message.

3

Dear akohlmey, many thanks for your reply. I am sorry for my incorrect expression. I have revised it.
When I use reax/c potential with setting “pair_style reax/c NULL”, there will always be one error reported appearing as “Pair reax/c requires use of fix qeq/reax or qeq/shielded”. In other words, I can’t use the command “pair_style reax/c NULL”.
Could you please help me, thank you.

4

This is documented behavior and not a bug. Please review the documentation for the pair style carefully. As the error message indicates, a correct realization of the ReaxFF force field requires the use of charge equilibration with one of the two listed fix commands.

You will see the same in all of the ReaxFF examples.

5

Hi dear Akohlemy,

I got the same error in running my program and I would be thankful if you could help me.
Error: Pair style reaxff requires use of exactly one of the fix qeq/reaxff or fix qeq/shielded or fix acks2/reaxff commands.

I just used Fix acks2/reaxff and I want to minimize my system before equilibration. when I use minimize and min_style commands in my input script I got the above Error but without using these commands it runs. I know that I could not use cg algorithms with acks2. But I do not know how I can minimize my system.?

min_style cg
minimize 1e-25 1e-25 500000 1000000

6

There is no problem in using minimization if following the documentation correctly. The error message is pretty much self-explanatory in that respect and the solution obvious.

In order to make this a topic worth discussing here you have to prove that a) you have followed the documentation in all aspects and b) provide a simple/small and easy to run and debug input deck that still fails under those conditions.

In the examples provided with LAMMPS that use acks2 it is easily possible to insert a minimization before running the dynamics.

7

Thank you for your response.

Kindly,