anchor.diff:  
                       if (sym == ref_sym) then
   
  -                        if (truncate_space) then
  -                            call encode_det(occ, f)
  -                            if (get_excitation_level(f,f0) <= truncation_level) then
  -                                ! Within truncation level.
  -                                idet = idet + 1
  -                                if (separate_strings) then
  -                                    ! Merge alpha and beta sets into determinant list.
  -                                    dets_list(:,idet) = (/ f_alpha, f_beta /)
  -                                else
  -                                    dets_list(:,idet) = f
  -                                end if
  -                            end if
  -                        else
  -                            idet = idet + 1
  -                            if (separate_strings) then
  -                                ! Merge alpha and beta sets into determinant list.
  -                                dets_list(:,idet) = (/ f_alpha, f_beta /)
  -                            else
  -                                call encode_det(occ, f)
  -                                dets_list(:,idet) = f
  -                            end if
  -                        end if
  +                        idet = idet + 1
  +                        call encode_det(occ, dets_list(:,idet))
   
                       end if
   
  
positive.code:             deallocate(dets_list, stat=ierr)
              call check_deallocate('dets_list',ierr)
          end if
  
          nbeta_combinations = binom_i(nbasis/2, nbeta)
          nalpha_combinations = binom_i(nbasis/2, nalpha)
  
          ndets = sym_space_size(ref_sym)
  
  
negative.code:                 ! Simply count the number of allowed determinants.
                  ! CBA to find the closed form for the Hubbard model with local
                  ! orbitals (ie no symmetry constraints).
  
                  ! Determinants are assigned a given symmetry by the direct product
                  ! of the representations spanned by the occupied orbitals.  For
  