anchor.diff:  step_flag=.false.
   align_flag=.false.
   ignoreH=.false.
  +peratom=.false.
   i=1
   cla=command_argument_count()
   if (cla==0) then
  
positive.code:  call usage_mess
   stop
  end if
  open(unit=9,file=xyzname)
  open(unit=10,file=outnameIR)
  open(unit=20,file=outnameVDOS)
  if (align_flag) open(unit=30,file=outnameAL)
  
negative.code:   grptags(ig)=elem
    ig=ig+1
   end if
  endif
  end do
  write(*,*) 'Found ',ig-1,' unique elements in trajectory file'
  !Rewind xyz file
  