Hi, the lammps user
I’m currently calculating VACF as a function of the distance between two materials
I used “fix spring/self” to restrain the center of mass distance between the two groups.
As below my scripts, I used “fix spring/self” at the equilibrium without the calculation of VACF and it worked.
It means that two groups had the initial position.
However, I added the calculation part of VACF, two groups close to each other. They did not keep initial position while calculating VACF.
If you tell me what’s wrong, I’d really appreciate it.
Thanks,
Jaeyoung Jeong
This is the control script for LAMMPS
echo both
Hi, the lammps user
I'm currently calculating VACF as a function of the distance between two
materials
I used "fix spring/self" to restrain the center of mass distance between
the two groups.
please note, that fix spring/self restrains *all* atoms to there initial
*individual* positions.
this will also restrain the COM distance between two groups implicitly, but
to *only* restrain that distance, you should use plain fix spring in couple
mode.
As below my scripts, I used "fix spring/self" at the equilibrium without
the calculation of VACF and it worked.
It means that two groups had the initial position.
However, I added the calculation part of VACF, two groups close to each
other. They did not keep initial position while calculating VACF.
If you tell me what's wrong, I'd really appreciate it.
using fix spring/self together with the intention to compute VACFs makes
no sense. you are significantly manipulating atomic velocities with this.
also, using fix momentum in this case pointless and very likely creating
issues as well.
axel.
Hi, Axel
Based on your comments, I used fix spring couple with 20 A distance as below the script.
The initial distance between graphene layer and Cu top layer was 20 A.
I checked the distance after NVE, graphene layer closed to Cu. They were at the initial position.
I’d appreciate it if you let me know what is wrong with my script.
Thanks,
Jaeyoung
This is the control script for LAMMPS
echo both
Hi, Axel
Based on your comments, I used fix spring couple with 20 A distance as
below the script.
The initial distance between graphene layer and Cu top layer was 20 A.
I checked the distance after NVE, graphene layer closed to Cu. They were
at the initial position.
I'd appreciate it if you let me know what is wrong with my script.
sorry, i don't have time to debug your input. more importantly, i don't
even see what you are asking here.
please ask more specific questions. LAMMPS will operate as specified in the
documentation, so if LAMMPS doesn't do what you expect, chances are high,
that you didn't read the documentation carefully enough or didn't
understand what was written. if you have difficulties figuring out how a
specific feature in LAMMPS works, then please set up a very simple test,
where you can compute the results by hand or easily observe the impact of
your commands or changes to parameters.
axel.