Dear lammps users
I used Reaxff forcefiled with pair_style reax/c. I have O,C,H atoms in my system. I want to equilibrium my system at 2500 K without chemical reactions, so I want to switch off the C-O and H-O bond parameters to prevent the reactions. My question is how to switch off C-O and H-O bond parameters in reax/c style. Thanks for the detailed suggestions
Fan Li
Dear lammps users
I used Reaxff forcefiled with pair_style reax/c. I have O,C,H atoms in my
system. I want to equilibrium my system at 2500 K without chemical
reactions, so I want to switch off the C-O and H-O bond parameters to
prevent the reactions. My question is how to switch off C-O and H-O bond
parameters in reax/c style. Thanks for the detailed suggestions
just use a non-reactive force field with explicit harmonic bonds.
axel.
Hi axel
My original purpose is to study the oxidation process at 2500 K and my simulation processes is listed here.
Firstly, I minimize my structure (mainly PAHs and aliphatic chain) using Dreiding force field which uses harmonic function form for bonds. And then I will use Reaxff focefiled with the C-O and H-O bond parameters off to equilibrium my structure with NVT at 2500 K. Finally, I will use Reaxff forcefiled to simulate the oxidation with NVT at 2500 K. (The last two steps are used by author of the Reaxff forcefiled to study the oxidation process.)
My question is if I also used Dreiding force field for equilibrium at 2500 K, whether the finally oxidation process will be affected or not.
In my opinion, the purpose of equilibrium is to find the reasonable structure at desired temperature, so using the Dreiding force field is also ok and using the non-reactive forcefiled will not affect the final oxidation process .But I am not sure. So would you mind giving me some explanation about choosing the non-reactive forcefiled at equilibrium stage? Thanks in advance.
Fan Li
Hi axel
My original purpose is to study the oxidation process at 2500 K and my
simulation processes is listed here.Firstly, I minimize my structure (mainly PAHs and aliphatic chain) using Dreiding
force field which uses harmonic function form for bonds. And then I will
use Reaxff focefiled with the C-O and H-O bond parameters off to
equilibrium my structure with NVT at 2500 K. Finally, I will use Reaxff
forcefiled to simulate the oxidation with NVT at 2500 K. (The last two
steps are used by author of the Reaxff forcefiled to study the oxidation
process.)My question is if I also used Dreiding force field for equilibrium at 2500
K, whether the finally oxidation process will be affected or not.In my opinion, the purpose of equilibrium is to find the reasonable
structure at desired temperature, so using the Dreiding force field is also
ok and using the non-reactive forcefiled will not affect the final
oxidation process .But I am not sure. So would you mind giving me some
explanation about choosing the non-reactive forcefiled at equilibrium
stage? Thanks in advance.
that is something you should discuss with your adviser and/or make some
tests and validate yourself. i may have some opinion, but i have no
particular experience with your specific system nor experience with the
specific parameterizations and their degree of transferability, so it would
be a useless opinion. how would you justify this in a paper describing your
finding? "some random guy i never met told me that it is ok to do this" ??
axel.
Hi axel
Yes, you are right. I should validate the results by myself. But, I do not know how to switch off C-O and H-O bond parameters in Reaxff forcefiled. Could you tell me how to do that in lammps?
Then I can compare the result using Reaxff focefiled and Dreiding force field at equilibrium stage.
Fan Li
In simple words, there is no such function in LAMMPS.
Ray Shan
Materials Design, Inc.
Thanks for answering my question.