Dear lammps users,
I want to use gran/hooke/history as pair potential, but two different
set of parameters for different atom types. For that I am using
pair_style hybrid command. But I don't know how to give different set
of parameters to different atom types. When I am using following
command it is showing
ERROR: Illegal pair_style command
pair_style hybrid gran/hooke/history 50000.0 NULL 100.0 NULL 0.4 1
gran/hooke/history 100000 NULL 50 NULL 0.4 1
pair_coeff * * gran/hooke/history 50000.0 NULL 100.0 NULL 0.4 1
pair_coeff 1 2 gran/hooke/history 100000 NULL 50 NULL 0.4 1
can anyone tell me how to use different set of pair coefficients for
different atom types for gran/hooke/history pair style.
Thanking you
Shantanu Maheshwari
You can’t call pair_style hybrid using the same style listed twice. You may be able to do what you want by creating a new pair style such as “gran/hooke/history2” which is the same as “gran/hooke/history” except for having a “2” in the name. You would have to recompile the code in order to use the new style. You should also make sure that this is a reasonable thing to do physically.
–AEI
But there should be some way to use different set of parameters for
different atom types and it is physically very common situation, as
you can have mixture of two different particles. It can be done easily
for other pair style, but I am not getting how to use it for
gran/hooke/history. Even if I recompile with extra "2", what script
should I use to run the simulation.
Thanking you
Shantanu Maheshwari
i don't think you can have multiple of these granular pair styles
because of technical reasons of their implementation.
But there should be some way to use different set of parameters for
different atom types and it is physically very common situation, as
you can have mixture of two different particles. It can be done easily
those parameters (e.g. radius) can be set with the atom type not with
pair coefficients.
cheers,
axel.
But in the manual it is written that "If a granular potential is used
as a sub-style of pair_style hybrid, then specific atom types can be
used in the pair_coeff command to determine which atoms interact via a
granular potential."
If granular potential can be used as sub style of pair_style hybrid,
then I think there must be some way to use different pair coefficients
for different atom types.
Thanking you
Shantanu Maheshwari
Right now, you can use gran/hooke/history as a substyle of hybrid, which means that only specific interactions use that poential. However, the coefficients will be the same for ALL types of interactions using the pair style.
If you wanted to have gran/hooke/history use different coefficients for different interactions, you would need to modify the code.
–AEI
But in the manual it is written that "If a granular potential is used
as a sub-style of pair_style hybrid, then specific atom types can be
used in the pair_coeff command to determine which atoms interact via a
granular potential."
If granular potential can be used as sub style of pair_style hybrid,
then I think there must be some way to use different pair coefficients
for different atom types.
no, this is not how the hybrid pair style works.
it allows to mix different potential _types_. if
the pair style supports using different coefficient pairs,
then this carries over to the hybrid style, if not then not.
perhaps you should explain what you want to achieve
and somebody that has more experience with granular
simulations than me can make a suggestion on how
to realize this.
cheers,
axel.
As Ahmed says, you can't do this with pair hybrid, with any potential,
i.e. use it twice. The gran hooke/history potential would have
to be extended itself to allow different params for different
atom types. No one has ever wanted to do that before.
Steve