[lammps-users] Is it possible to turn off 1-5 interaction for Stillinger-Weber type atoms?

LAMMPS LAMMPS Mailing List Mirror
1

Hello Lammps Users & Developers,

I am trying to simulate a molecule with hybrid atom types (SW and lj/cut). In my simulation, I wanted to turn off 1-5 interaction along with 1-4 interaction. I could turn off 1-4 interaction by special_bonds settings as lj 0.0 0.0 0.0 diheddral yes angle yes. However, it seems that I could not turn off 1-5 interactions with special bond_style, as the 1-5 interactions I wanted to turn off are between SW types. In the manual, it is written that it is not generally applicable for many body potentials. Thus, I was wondering whether there is any other way by which I could turn off this 1-5 interaction. Please note that I am using lammps 29Oct 2020 version and I have defined the bonds corresponding to the 1-5 pairs in bond sections of data file. Here I am writing the part of my input file where I am defining these stuff

special_bonds lj 0.0 0.0 0.0 angle yes dihedral yes

pair_style hybrid sw lj/cut 12.0
bond_style hybrid harmonic special

read_data gly.data

bond_coeff 2 harmonic 30 1.43 # C-O
bond_coeff 3 harmonic 30 1.43 # C-O
bond_coeff 1 harmonic 30 1.53 # C-C
bond_coeff 4 special 0.0 0.0

Also, I wanted to tune the 1-4 interactions between SW type atoms, which seem not to be working although it is clearly written in the manual that many body potentials are insensitive to special_bonds settings. Thus, I was wondering whether there is any other way for this. Any help would be appreciated.

Thanks in advance!

Prabir

2

bond style special requires that pair styles between the pairs are pairwise additive, i.e. have a “single” method. The sw pair style does not fall into that category.
I do not want to go into details discussing the meaning of excluding manybody interactions for molecules, but what you are asking for is simply not possible in LAMMPS currently.

3

Thank you, Axel!