anchor.diff:  
   !--- Attempt to find a reasonable reference determinant ---
   
  -    subroutine set_reference_det(occ_list, override_input)
  +    subroutine set_reference_det(occ_list, override_input, ref_sym)
   
           ! Set the list of occupied orbitals in the reference determinant to be
           ! the spin-orbitals with the lowest kinetic energy which satisfy the
  
positive.code:         ! definition of 'best' is system dependent (see code below).
  
          ! In/Out:
          !   occ_list: allocatable integer array.  Contains the reference
          !   determinant (nel elements) on output.  Unchanged if already
          !   allocated unless override_input is set.
          ! In:
          !   override_input: if true, overwrite occ_list with the best guess of
          !   a reference determinant even if occ_list is allocated on input.
  
          use checking, only: check_allocate
  
          use errors, only: stop_all
          use system, only: nalpha, nbeta, nel, system_type, hub_k, hub_real, read_in, ueg, nsites, &
                            heisenberg, J_coupling
          use basis, only: bit_lookup
          use hubbard_real, only: connected_orbs
  
          integer, intent(inout), allocatable :: occ_list(:)
          logical, intent(in) :: override_input
  
          integer :: i, j, ierr, spins_set, connections
          integer :: bit_element, bit_pos
          logical :: set
  
          ! Leave the reference determinant unchanged if it's already been
  
negative.code: 
      end subroutine set_reference_det
  
  end module reference_determinant
  