anchor.diff:          call bulk_reaction(solvent, solvent_cells, 2, 1, bulk_rate(2), tau, state)
        end if
   
  -     n_solvent = 0
  -     do k = 1, solvent%Nmax
  -        j = solvent%species(k)
  -        if (j <= 0) continue
  -        n_solvent(j) = n_solvent(j) + 1
  -     end do
  -     call n_solvent_el%append(n_solvent)
  -
  +     if (sampling) then
  +        n_solvent = 0
  +        do k = 1, solvent%Nmax
  +           j = solvent%species(k)
  +           if (j <= 0) continue
  +           n_solvent(j) = n_solvent(j) + 1
  +        end do
  +        call n_solvent_el%append(n_solvent)
  +     end if
   
     end do
     call main%tac()
     write(*,*) ''
   
     write(*,*) 'n extra sorting', n_extra_sorting
  +
  +  call thermo_data%append(hfile, temperature, e1+e2+e3, kin_e, e1+e2+e3+kin_e, &
  +       v_com, add=.false., force=.true.)
   
     ! create a group for block correlators and write the data
   
  
positive.code:   colloids%pos(2,3) = colloids%pos(2,3) + link_d(2)*sin(link_angle)
    
    call n_solvent_el%create_time(hfile%observables, 'n_solvent', &
         n_solvent, H5MD_LINEAR, step=N_MD_steps, &
         time=N_MD_steps*dt)
  
    call h5gcreate_f(dimer_io%group, 'box', box_group, error)
  
negative.code: 
    double precision :: e1, e2, e3
    double precision :: tau, dt , T
    double precision :: skin, co_max, so_max
    integer :: N_MD_steps, N_loop
    integer :: n_extra_sorting
  