anchor.diff:  step_flag=.false.
   align_flag=.false.
   ignoreH=.false.
  +peratom=.false.
   i=1
   cla=command_argument_count()
   if (cla==0) then
  
positive.code:  do
    read(9,*,iostat=ioerror)
    if (ioerror.lt.0) then
     exit
    else if (ioerror.gt.0) then
     write(*,*) 'READ ERROR'
     stop
    end if
    read(9,*) cstep, energy, scrdip
  
negative.code:  else if (trim(arg)=='-ignH') then
    ignoreH=.true.
    i=i+1
   else if (trim(arg)=='-peratom') then
    peratom=.true.
    i=i+1
   else
    write(*,*)
    write(*,*) 'Unrecognized option:', TRIM(arg)
  