question about fix setforce

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1

Hello,

I use “fix setforce” command on a group of atoms but I want to know if there is a way to extract the force(s) on these atoms from other atoms outside the group (I mean force before it is zeroed by fix setforce).

thanks,
Anurag

2

See the bottom of the fix setforce doc page. The
fix stores exactly the quantity you are asking about,
which can be output.

Steve

3

Hello Everyone,

I had a question regarding generation of a parallelepiped using “region prism” command.

is there a reason to allow only 3 “tilt factors” ?

right now the documentation says the allowed “tilt factors” are xy, xz and yz. I was wondering why a factor such as zx is not allowed ?

thank you.

regards,
Anurag

4

Hello Everyone,

I had a question regarding generation of a parallelepiped using "region
prism" command.

is there a reason to allow only 3 "tilt factors" ?

that is sufficient to describe all meaningful system cells.

right now the documentation says the allowed "tilt factors" are xy, xz and
yz. I was wondering why a factor such as zx is not allowed ?

the implementation for non-orthogonal cells requires
the first axis of the system cell being collinear with the
the x-axis, the second axis to be in the xy plane and
the third chosen so that you get a right-handed coordinate
system. that limits the choices to these three.

axel.

5

Another way to look at it, is that any general parallelpiped
can be rotated to be compatible with the 3 tilt
factors that LAMMPS allows.

Steve

6

Hello,

I am running a simulation wherein MS static runs follow a MD (NVE+Langevin thermostat) run.

I see LAMMPS prints a warning saying :

WARNING: Resetting reneighboring criteria during minimization (min.cpp:167)

what does this imply ? this seems to imply that neighbour list settings specified for MD run are reset but what are the changed settings for building neighbor lists?

thanks.

7

Hello,

I am running a simulation wherein MS static runs follow a MD (NVE+Langevin
thermostat) run.

I see LAMMPS prints a warning saying :

WARNING: Resetting reneighboring criteria during minimization (min.cpp:167)

what does this imply ? this seems to imply that neighbour list settings
specified for MD run are reset but what are the changed settings for
building neighbor lists?

the changed settings are

neigh_modify delay 0 every 1

the original settings are stashed away and
then restored at the end of the minimization.

btw: this topic was explained on this very
mailing list recently already.

axel.