   def  rrr = reff/10
   path(1, feff=../feff/feff0001.dat, delr=rrr)
   path(2, feff=../feff/feff0002.dat, delr=rrr)
   ff2chi(1,2,group=x)
   echo 'aa' 
   show rrr

   set path_index = 1
   echo 'bb' 
   show rrr, path_index

   path_index = 2
   show rrr



