LAMMPS WWW Site - LAMMPS Documentation - LAMMPS Mailing List Archives
[lammps-users] problem with special_bonds
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[lammps-users] problem with special_bonds


From: Juan Antonio Seijas Bellido <juaseibel@...24...>
Date: Mon, 30 Apr 2018 17:20:41 +0200

Hello, I am working with the buck/coul/long/cs potential and a core-shell model, so I want to remove the Coulomb interaction between all the cores and their own shells. To do that, I am using the command:  special_bonds coul 0.0 1.0 1.0
but if I print the forces over each atom of the system there is no difference between using the command or not. I think I am doing something wrong but I don't know what. Can you tell me what I have to do? I leave here my input and the file with the coordinates, which is the groung state with a shell displaced by me to not have zero force. In both cases (with and without the special_bonds command) I obtain this force for the first shell (second atom): 2 3 -2.20213 -3.37996 -6.88967


Thank you very much for your attention.
Juan

input file
------------
 units        metal
 boundary     p p p
 atom_style   full

 read_data    coord.dat

 kspace_style ewald 1.0e-5
 pair_style   buck/coul/long/cs 8.5
 pair_coeff * *      0.0  1.0      0.0
 pair_coeff 3 4    499.6  0.3595   0.0
 pair_coeff 4 4  22764.0  0.1490  27.88

 bond_style harmonic
 bond_coeff 1 4.385 0.0
 bond_coeff 2 7.760 0.0
 special_bonds coul 0.0 1.0 1.0

 dump name_dump all custom 1 forces_LAMMPS id type fx fy fz
 dump_modify name_dump sort id

run 1


coord.dat
-------------
LAMMPS empty line

    16 atoms    # core and shell atoms
     8 bonds    # number of core/shell springs

 4 atom types   # 2 cores and 2 shells for Zn and O
 2 bond types

 0.00000000   3.2328763 xlo xhi
 0.00000000   5.5994991 ylo yhi
 0.00000000   5.1807427 zlo zhi

 Masses

 1 58.842    # Zn core
 2 14.39946  #  O core
 3 6.538     # Zn shell
 4 1.59994   #  O shell

 Atoms

 1 1 1  -0.05 0.000000000000000000   0.000000000000000000   0.000000000000000000
 2 1 3   2.05 0.200000000000000000   0.200000000000000000   0.200000000000000000
 3 2 1  -0.05 3.232473748343905218   1.928674177488681973   2.469640121135010524
 4 2 3   2.05 3.232473748343905218   1.928674177488681973   2.469640121135010524
 5 3 1  -0.05 1.616038132398342819   2.861891922558703616   5.060007410266783801
 6 3 3   2.05 1.616038132398342819   2.861891922558703616   5.060007410266783801
 7 4 1  -0.05 1.616038258394003835   4.728419338484792789   2.469640121238056096
 8 4 3   2.05 1.616038258394003835   4.728419338484792789   2.469640121238056096
 9 5 2   0.00 3.232473874375850986   0.062146505458974266   1.880772821867820355
10 5 4  -2.00 3.232473874375850986   0.062146505458974266   1.880772821867820355
11 6 2   0.00 3.232473748346172737   1.928674433776235375   4.471140110972311454
12 6 4  -2.00 3.232473748346172737   1.928674433776235375   4.471140110972311454
13 7 2   0.00 1.616038132335708477   2.861891666290283798   1.880772821859789889
14 7 4  -2.00 1.616038132335708477   2.861891666290283798   1.880772821859789889
15 8 2   0.00 1.616038258417267226   4.728419594758751288   4.471140110974821447
16 8 4  -2.00 1.616038258417267226   4.728419594758751288   4.471140110974821447

 Bonds

1 1 1 2
2 1 3 4
3 1 5 6
4 1 7 8
5 2 9 10
6 2 11 12
7 2 13 14
8 2 15 16