... and in the first example, if you want to limit the files by the number that appears in the filename, one way to do that is:

for my $file (glob '1M01_F*.npt.gro') {
  next unless $file=~/^1M01_F(\d{5})\.npt\.gro$/
    && $1>120 && $1<=150;
  print "$file\n";
}
__END__
1M01_F00121.npt.gro
1M01_F00130.npt.gro
1M01_F00140.npt.gro
1M01_F00150.npt.gro
[download]

The doubling of the filename pattern may not be particularly elegant though. Other ways to list files in a directory include readdir, File::Find (which goes into subdirectories too), Path::Class, or Path::Tiny.