Thank you Axel for the answer,
So you are saying that the statement
"The forces due to this fix are imposed
during an energy minimization"
means "if YOU perform a minimization then that minimization will take in
account addtorque" .
yes, not all fixes are invoked during minimization.
Maybe i'm confused because the behaviour that i observe in my rigid body
is similar to the one described in the minimize doc page "...the energy
minimization will not keep the defined body(s) rigid during the
minimization."
please look at the corresponding section of the fix rigid docs, where it says:
These fixes are not invoked during energy minimization.
so when you issue, the "minimize" command, fix rigid will have no
effect. it will only be invoked when using the "run" command.
Here is the infile in a synthetic version:
the rigid-body is constitued by two rows of grains partially overlapped
along the x-axis and the z-axis.
I apply a constant torque respect to the z-axis so i expect that the
rows will rotate with an increasing angular velocity without changing
their z height and the relative positions between the grains.
On the contrary, what i observe in the dump file is that the z
coordinates of the particles change and the rigid body is deformed after
some timesteps.
what do you think is going wrong?
i don't know what is happening here. it works as expected for me with
the following simple input based on the melt example, so i suspect it
is due to something that you don't show us.
lattice fcc 0.8442
region box block -10 10 -10 10 -10 10
create_box 2 box
#region rotate cylinder z 0.0 0.0 7.0 -5.0 5.0
region rotate block -6.0 6.0 -6.0 6.0 -5.0 5.0
create_atoms 2 region rotate
mass * 1.0
velocity all set 0.0 0.0 0.0
pair_style lj/cut 2.5
pair_coeff * * 1.0 1.0 2.5
neighbor 0.3 bin
neigh_modify every 2 delay 2 check yes exclude type 2 2
fix 0 all addtorque 0.0 0.0 100.0
#fix 1 all rigid single
fix 1 all rigid single torque 1 off off on force 1 off off off
#dump id all atom 50 dump.melt
#dump 2 all image 25 image.*.jpg type type &
# axes yes 0.8 0.02 view 60 -30
#dump_modify 2 pad 3
#dump 3 all movie 100 movie.mpg type type &
# axes yes 0.8 0.02 view 60 -30
#dump_modify 3 pad 3
thermo 500
run 10000
axel.