group/group command for granular pair

Submitted by SHUBHAM AGARWAL on Wed, 10/28/2020 - 20:59

Hello
I am currently using LIGGGGHTS-flexible fibers version for granular bonds.
In my simulation I have 2 groups (web & blade), and I want to calculate the force that web exerts on the blade. For that I tried the following command:
compute force_inter blade group/group web

However, I am encountering the error saying that "Pair style does not support group/group".
In the contact style, I am using the following:
"pair_style gran model hertz tangential history "

Can someone please help me to resolve this

Thanks

Forums:

mschramm | Wed, 10/28/2020 - 22:55

Hello,
I did a grep search in the source code for "single_enable = 1". This is what is causing the error.
It appears that no pair_style in LIGGGHTS supports this so it may be dead code. Someone from LIGGGHTS will need to give a concreate answer.

Since no pair_style set this value to 1, I also checked in my local version of LAMMPS.
Here I found that they set it to one for the following pair types:
pair_gran_hooke_history
pair_gran
pair_python
pair_lj_sdk
pair_local_density
pair_buck6d_coul_gauss_dsf
pair_buck6d_coul_gauss_long

This suggests that you may have some luck in getting the command to work for the hooke pair style but you will need to compare the LAMMPS code to LIGGGHTS to see if there is any differences between how LIGGGHTS implements the hooke pair_style vs LAMMPS implementation.