anchor.diff:    shift = max(sigma_C, sigma_N)*2**(1./6.) + 0.25
     call walls_colloid_lj% init(epsilon(1:1,:), sigma(1:1,:), sigma_cut(1:1,:), shift)
   
  -  write(*,*) epsilon(1:2,:), sigma(1:2,:), sigma_cut(1:2,:), shift
  -
     allocate(mass(N_colloids))
     if (dimer) then
        mass(1) = rho * sigma_C**3 * 4 * 3.14159265/3
  
positive.code:   on_track = .true.
    stopped = .false.
  
    write(*,*) colloids% pos
    solvent_cells%bc = [PERIODIC_BC, SPECULAR_BC, BOUNCE_BACK_BC]
  
    write(*,*) 'Running for', N_loop, 'loops'
  
negative.code:   double precision :: colloid_pos(3,2)
    type(h5md_file_t) :: hfile
    type(h5md_element_t) :: dummy_element
    integer(HID_T) :: fields_group, params_group
    type(h5md_element_t) :: rho_xy_el
    type(thermo_t) :: thermo_data
    type(particle_system_io_t) :: dimer_io
  