anchor.diff:       call solvent_cells%random_shift(state(1))
        call varia%tac()
   
  +     call apply_pbc(solvent, solvent_cells% edges)
  +     call apply_pbc(colloids, solvent_cells% edges)
        call solvent% sort(solvent_cells)
  -     call neigh% update_list(colloids, solvent, max_cut+skin, solvent_cells)
  +     call neigh% update_list(colloids, solvent, max_cut+skin, solvent_cells, solvent_colloid_lj)
        call varia%tic()
        !$omp parallel do
        do k = 1, solvent%Nmax
  
positive.code: 
    call neigh% make_stencil(solvent_cells, max_cut+skin)
  
    call neigh% update_list(colloids, solvent, max_cut+skin, solvent_cells)
  
    cyl_shell_rmin = max(sigma_N, sigma_C)
    cyl_shell_rmax = cyl_shell_rmin + 2
  
negative.code:            call apply_pbc(colloids, solvent_cells% edges)
             call varia%tac()
             call solvent% sort(solvent_cells)
             call neigh% update_list(colloids, solvent, max_cut + skin, solvent_cells, solvent_colloid_lj)
             call varia%tic()
             !$omp parallel do
             do k = 1, solvent%Nmax
  