Dear Lammps users:
I use fix print to output some data into a file, but I found that I am confused with the function of the group-ID in this command.
For example, I define a variable like variable mytemp equal temp and output it through fix output all print 100 "\{mytemp\}" file output1\.txt\. The temperature will be written to the file output\.txt\. If I divided the system into two groups named group1 and group2\. The command fix output group1 print 100 "{mytemp}" file output1.txt will give me the same output results.
It seems usually change of group-ID will not alter the output results. Could anybody tell me the role of group-ID it plays?
Thanks very much!
With Best Regards
Liu
Dear Lammps users:
I use fix print to output some data into a file, but I found that I am
confused with the function of the group-ID in this command.
For example, I define a variable like variable mytemp equal temp and output
it through fix output all print 100 "\{mytemp\}" file output1\.txt\. The
temperature will be written to the file output\.txt\. If I divided the system
into two groups named group1 and group2\. The command fix output group1 print
100 "{mytemp}" file output1.txt will give me the same output results.
It seems usually change of group-ID will not alter the output results. Could
anybody tell me the role of group-ID it plays?
for fix print, it is ignored. a group id has to be specified for
implementation reasons for *all* fix styles, but in this case it has
no meaning.
if you want to compute (and output) the temperature for a subsystem,
you have to define two temperature computes that are restricted to
those respective groups and then print the global scalar of those
computes. the "temp" thermo keyword works in the same way, but it is
by default linked to a temperature compute for the group "all".
axel.