Changing values of LJ potential during a simulation

Thank you for your very fast answer!

please always send a copy of your replies to the mailing list. thanks.

Now it works!

i have another little question, sometimes when my simulations crash, i
got lots of core.****** (*=number) in my simulation folder. This files
are about 100MB and they occupy most of the space i got on my
simulation cluster.
Are they created by Lammps? And is it possible to not create them?

if programs crash, e.g. with a segmentation fault, those core.*
files are usually created. you can in principle turn this off from
the shell level, but in this case, you should better talk to the
person running the simulation cluster, because this will happen
to everybody and unless people are doing debugging, it is just
wasting disk space.

which command you have to use to turn off core dumps depends
on the shell program you use. best you search on the web, and
there you can also learn what those files can be used for in debugging,