anchor.diff:    allocate(rho_xy(N_species, L(2), L(1)))
     call h5gcreate_f(hfile%id, 'fields', fields_group, error)
     call rho_xy_el%create_time(fields_group, 'rho_xy', rho_xy, ior(H5MD_LINEAR,H5MD_STORE_TIME), &
  -       step=N_loop*N_MD_steps, time=N_loop*N_MD_steps*dt)
  +       step=N_MD_steps, time=N_MD_steps*dt)
     call h5gclose_f(fields_group, error)
  +
  +  call n_solvent_el%create_time(hfile%observables, 'n_solvent', &
  +       n_solvent, ior(H5MD_LINEAR,H5MD_STORE_TIME), step=N_MD_steps, &
  +       time=N_MD_steps*dt)
  +  call catalytic_change_el%create_time(hfile%observables, 'catalytic_change', &
  +       catalytic_change, ior(H5MD_LINEAR,H5MD_STORE_TIME), step=N_MD_steps, &
  +       time=N_MD_steps*dt)
  +  call bulk_change_el%create_time(hfile%observables, 'bulk_change', &
  +       bulk_change, ior(H5MD_LINEAR,H5MD_STORE_TIME), step=N_MD_steps, &
  +       time=N_MD_steps*dt)
   
     colloids% pos(3,:) = solvent_cells% edges(3)/2.d0
     if (order) then
  
positive.code:           (solvent%Nmax + mass(1) + mass(2))
       call thermo_data%append(hfile, temperature, e1+e2+e_wall, kin_e, e1+e2+e_wall+kin_e, v_com)
  
       call dimer_io%position%append(colloids%pos)
       call dimer_io%velocity%append(colloids%vel)
       call dimer_io%image%append(colloids%image)
  
negative.code:   integer :: N_MD_steps, N_loop
    integer :: n_extra_sorting
    double precision :: kin_e, temperature
    integer, dimension(N_species) :: n_solvent, catalytic_change, bulk_change
    type(h5md_element_t) :: n_solvent_el, catalytic_change_el, bulk_change_el
  
    double precision :: conc_z(400)
    double precision :: colloid_pos(3,2)
  