anchor.diff:                              isymb = sys%read_in%sym_conj_ptr(sys%read_in, &
                                       sys%read_in%cross_product_sym_ptr(sys%read_in, ij_sym, sys%basis%basis_fns(a)%sym))
                               do b = 1, sys%basis%nbasis 
  -                                if (((sys%basis%basis_fns(i_tmp)%Ms == sys%basis%basis_fns(a)%Ms) .and. &
  +                                if ((((sys%basis%basis_fns(i_tmp)%Ms == sys%basis%basis_fns(a)%Ms) .and. &
                                       (sys%basis%basis_fns(j_tmp)%Ms == sys%basis%basis_fns(b)%Ms)) .or. &
                                       ((sys%basis%basis_fns(i_tmp)%Ms == sys%basis%basis_fns(b)%Ms) .and. &
  -                                    (sys%basis%basis_fns(j_tmp)%Ms == sys%basis%basis_fns(a)%Ms)) .and. &
  +                                    (sys%basis%basis_fns(j_tmp)%Ms == sys%basis%basis_fns(a)%Ms))) .and. &
                                       (sys%basis%basis_fns(b)%sym == isymb) .and. (a /= b) .and. (b /= i_tmp) .and. &
                                       (b /= j_tmp)) then
                                       if (b < a) then
  
positive.code:                 if ((a /= pp%occ_list(i)) .and. (sys%basis%basis_fns(a)%sym == isyma) .and. &
                      (sys%basis%basis_fns(a)%ms == ims)) then
                      i_weight = i_weight + single_excitation_weight_ptr(sys, pp%occ_list(i), a)
                      print *, pp%occ_list(i), a, i_weight 
                  end if
              end do
              if (i_weight < depsilon) then
  
negative.code:                                         sys%read_in%cross_product_sym_ptr(sys%read_in, ij_sym, sys%basis%basis_fns(a)%sym))
                              do b = 1, sys%basis%nbasis
                                  ! Check spin conservation and symmetry conservation.
                                  if ((((sys%basis%basis_fns(i_tmp)%Ms == sys%basis%basis_fns(a)%Ms) .and. &
                                      (sys%basis%basis_fns(j_tmp)%Ms == sys%basis%basis_fns(b)%Ms)) .or. &
                                      ((sys%basis%basis_fns(i_tmp)%Ms == sys%basis%basis_fns(b)%Ms) .and. &
                                      (sys%basis%basis_fns(j_tmp)%Ms == sys%basis%basis_fns(a)%Ms))) .and. &
                                      (sys%basis%basis_fns(b)%sym == isymb) .and. (b /= a) .and. (b /= i_tmp) .and. &
                                      (b/=j_tmp)) then
                                      if (b < a) then
  