anchor.diff:        org_i = sort_idx(i,2)
         do j=shortcut(sh,2),i-1
           org_j = sort_idx(j,2)
  -        ext = 0
  -        do ni=1,Nint
  +        ext = popcnt(xor(sorted(1,i,2), sorted(1,j,2)))
  +        if (ext > 4) cycle
  +        do ni=2,Nint
             ext = ext + popcnt(xor(sorted(ni,i,2), sorted(ni,j,2)))
             if (ext > 4) exit
           end do
  
positive.code:   !$OMP DO SCHEDULE(dynamic)
    do sh=1,shortcut(0,1)
      do sh2=sh,shortcut(0,1)
        exa = 0
        do ni=1,Nint
          exa = exa + popcnt(xor(version(ni,sh,1), version(ni,sh2,1)))
        end do
        if(exa > 2) then
  
negative.code:           sorted_i(ni) = sorted(ni,i,1)
          enddo
          
   jloop: do j=shortcut(sh2,1),endi
            org_j = sort_idx(j,1)
            ext = exa + popcnt(xor(sorted_i(1), sorted(1,j,1)))
            if(ext > 4) then
              cycle jloop
            endif
            do ni=2,Nint
              ext = ext + popcnt(xor(sorted_i(ni), sorted(ni,j,1)))
              if(ext > 4) then
                cycle jloop
              endif
            end do
            call i_H_j(keys_tmp(1,1,org_j),keys_tmp(1,1,org_i),Nint,hij)
            do istate=1,N_st
              vt (istate,org_i) = vt (istate,org_i) + hij*ut(istate,org_j)
              vt (istate,org_j) = vt (istate,org_j) + hij*ut(istate,org_i)
            enddo
          enddo jloop
        enddo
      enddo
    enddo
  