fix print with none sequential time

Dear lammps users, :slight_smile:

I'm trying to print part of my data to a file using fix print. But the problem is I don't need my output data in a sequential time like every 100 time steps. So basically I'm trying to do something like below:

   fix VACF_out_print all print v_s "\{t\} {diff} \{vacf1\} {vacf2} \{vacf3\} {vacf4}" append VelAutoCoDiff.txt screen no

in which "s" is a variable containing the time intervals which I need. This time steps has been read by lammps via an input file like:

   variable f file logpointsquench.dat
   variable s equal next(f)

So the idea came from the fact that I have already used this method for outputting some other data, but with dump and dump modify as below :

   dump my_dump all custom 1 sort/out* id xu yu zu
   dump_modify my_dump append no every v_s sort id format line "%d %20.15g %20.15g %20.15g"

The problem is I can not use dump for VACF as is works with particle IDs and prints out per/atom data. That's why I'm trying to use fix print but it does not work.

First of all the variable should be given to it like ${s} and then it does not understand that it should print the data at every specific time step which v_s has.

So does any of you have any idea whether it is possible to modify fix print to write data in a none sequential time or not?

Regards
Mehrdad

Dear lammps users, :slight_smile:

I'm trying to print part of my data to a file using fix print. But the
problem is I don't need my output data in a sequential time like every
100 time steps. So basically I'm trying to do something like below:

   fix VACF_out_print all print v_s "\{t\} {diff} \{vacf1\} {vacf2} \{vacf3\} {vacf4}" append VelAutoCoDiff.txt screen no

in which "s" is a variable containing the time intervals which I need.
This time steps has been read by lammps via an input file like:

   variable f file logpointsquench.dat
   variable s equal next(f)

So the idea came from the fact that I have already used this method for
outputting some other data, but with dump and dump modify as below :

   dump my_dump all custom 1 sort/out* id xu yu zu
   dump_modify my_dump append no every v_s sort id format line "%d
%20.15g %20.15g %20.15g"

The problem is I can not use dump for VACF as is works with particle IDs
and prints out per/atom data. That's why I'm trying to use fix print but
it does not work.

First of all the variable should be given to it like ${s} and then it
does not understand that it should print the data at every specific time
step which v_s has.

So does any of you have any idea whether it is possible to modify fix
print to write data in a none sequential time or not?

‚Äčsure. you have the source code, so you can modify it as you wish.

axel.