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Re: [lammps-users] ERROR: All pair coeffs are not set (../pair.cpp:228)
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Re: [lammps-users] ERROR: All pair coeffs are not set (../pair.cpp:228)


From: Axel Kohlmeyer <akohlmey@...24...>
Date: Fri, 14 Jul 2017 14:42:04 -0400

On Fri, Jul 14, 2017 at 2:28 PM, Sharma MD <sa.md.dtm@...24...> wrote:
> Hello all,
> I am using hybrid pair style under which i am using two tersoff potentials.
> With first tersoff i am taking the interaction between Be and C and then
> switched off the interaction of C and C, which is given by the second
> tersoff potential. But the error is coming as all pair coeff are not set.
>
> # There are three types of atoms Cu, Be and C. Cu:1-3, Be-4, C:5-7.
>
> pair_style hybrid tersoff morse 2.5 eam
>
> pair_coeff * * tersoff BeC.abop.tersoff NULL NULL NULL Be C C C
> neigh_modify exclude type 5 5
> neigh_modify exclude type 5 6
> neigh_modify exclude type 5 7
> neigh_modify exclude type 6 6
> neigh_modify exclude type 6 7
> neigh_modify exclude type 7 7
> pair_coeff * * tersoff C.abop.tersoff NULL NULL NULL NULL C C C
> pair_coeff 1*3 5*7 morse 0.087 5.14 2.05
> pair_coeff 1*3 1*3 eam Cu_u3.eam
> pair_coeff 1*3 4 morse  2.14 5 2.065
>
>
> # Kindly suggest the way to cater Be and C and then C-C interaction
> separately

this can only be done by providing a single tersoff potential file.
tersoff interactions are not pairwise additive and thus cannot be
treated like that as you do in your input. even merging two parameter
sets as you seem to be intending to do (and would have to do manually
with a text editor), is rarely a good idea, as you will break the
balance between all parameters from the parameterization.

axel.

>
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-- 
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.