LAMMPS WWW Site - LAMMPS Documentation - LAMMPS Mailing List Archives
Re: [lammps-users] Solid state materials combustion
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [lammps-users] Solid state materials combustion


From: Axel Kohlmeyer <akohlmey@...24...>
Date: Tue, 4 Jul 2017 11:42:08 -0400

On Mon, Jul 3, 2017 at 8:46 PM, renefbg <renefbg@...6901...> wrote:
> Sorry for such a simple question, but I am having trouble in simulating the
> decomposition/combustion/explosion of some materials, starting in solid
> state.
>
> The structure of the crystal/molecules is totally changed in the first
> iteraction.
>
> I am using ReaxFF and building the data file using VMD, after creating the
> molecule file using avogadro and then creating the crystal structure using
> packmol (basically I used the crystal lattice parameters and inserted a
> certain amount of molecules to achieve the near-experimental density). Maybe
> packmol is creating a high energy distribution?

if your system has a high potential energy, you should see it in your
thermodynamic output.
if that is high, you could run a minimization (as it standard
procedure in MD) as initial part of your equilibration.

another common beginner's mistake with reaxff, is to generate a data
file with bonds/angles/dihedrals etc. those are computed dynamically
and providing them explicitly is an error, as it will change the force
field interactions.

> I even tried to use the fix rigid command, but it keeps the material from
> decomposing over time.

finally, you have to carefully check the force field parameters. you
need a set that is specifically parameterized for your kind of system.
reaxff is very specific and the resulting parameter sets are not very
transferable.

axel.

>
> Thanks for any suggestions.
>
>
>
> --
> Prof. Dr. Rene F. B. Gonçalves
> Departamento de Química
> Instituto Tecnológico de Aeronáutica
> Tel: +55 12 3947-6852
> Sec: +55 12 3947-5845
>
>
> ------------------------------------------------------------------------------
> Check out the vibrant tech community on one of the world's most
> engaging tech sites, Slashdot.org! http://sdm.link/slashdot
> _______________________________________________
> lammps-users mailing list
> lammps-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/lammps-users
>



-- 
Dr. Axel Kohlmeyer  akohlmey@...24...  http://goo.gl/1wk0
College of Science & Technology, Temple University, Philadelphia PA, USA
International Centre for Theoretical Physics, Trieste. Italy.