diff --git a/src/io.f90 b/src/io.f90
index 90efe0f..853a230 100644
--- a/src/io.f90
+++ b/src/io.f90
@@ -150,7 +150,7 @@ module io
     subroutine write_lmp(file)
         !This subroutine writes out a .lmp style dump file
         character(len=100), intent(in) :: file
-        integer :: write_num, i, iatom, type_interp(max_basisnum*max_esize**3)
+        integer :: write_num, i, iatom, type_interp(max_basisnum*max_esize**3), interp_num
         real(kind=dp) :: r_interp(3, max_basisnum*max_esize**3), mass
 
         open(unit=11, file=trim(adjustl(file)), action='write', status='replace',position='rewind')
@@ -192,13 +192,15 @@ module io
         end do
 
         !Write refined element atomic positions
+        interp_num = 0
         do i = 1, ele_num
             call interpolate_atoms(type_ele(i), size_ele(i), lat_ele(i), r_node(:,:,:,i), type_interp, r_interp)
             select case(trim(adjustl(type_ele(i))))
             case('fcc')
                 do iatom = 1, basisnum(lat_ele(i))*size_ele(i)**3
+                    interp_num = interp_num+1
                     call apply_periodic(r_interp(:,iatom))
-                    write(11, '(2i16, 3f23.15)') atom_num+iatom, type_interp(iatom), r_interp(:,iatom)
+                    write(11, '(2i16, 3f23.15)') atom_num+interp_num, type_interp(iatom), r_interp(:,iatom)
                 end do
             end select
         end do