documentation ambiguity

Hi Steve,

I have been running with one block of atoms controlled by ‘fix move’, and the remainder controlled by ‘fix nve’

I found an issue with my dynamics. To test, I used ‘fix dt/reset’ to see if I could narrow down where my problem was.

However, the code stopped with “ERROR Resetting timestep is not allowed with fix move (…/fix_move.cpp 1013)”.

The doc page for ‘fix move’ notes that resetting the timestep after reading a restart file may give an odd behaviour, but no ‘restrictions’ are listed.

Is this correct?


The error means that resetting the time step “size”
is not permitted, not the timestep itself. That is
b/c the various formulas used by fix move depend
on elapsed time from some time origin
and the motion may not be continuous
if the timestep size changes.



I accept the reasoning; I wanted to point out that whilst the page says ‘you may get garbage’, there is no mention that this will cause LAMMPS to stop with an ERROR.


I don’t see the garbage phrase on any doc page.
Which version of the doc pages are you looking at,
the current version?


Sorry Steve.

What I meant was that the phrase “
tells me that doing this will produce garbage. However, it does not say that “resetting the timestep with ‘fix dt/reset’ will cause LAMMPS to stop”.