anchor.diff:  
     write(*,*) 'n extra sorting', n_extra_sorting
   
  +  call dimer_io%close()
     call hfile%close()
     call h5close_f(error)
   
  
positive.code: 
       call thermo_data%append(hfile, temperature, e1+e2, kin_e, e1+e2+kin_e)
  
       solvent_cells% origin(1) = threefry_double(state(1)) - 1
       solvent_cells% origin(2) = threefry_double(state(1)) - 1
       solvent_cells% origin(3) = threefry_double(state(1)) - 1
  
negative.code:   call hfile%create(PTread_s(config, 'h5md_file'), 'RMPCDMD::single_dimer_pbc', &
         'N/A', 'Pierre de Buyl')
    call thermo_data%init(hfile, n_buffer=50, step=N_loop, time=N_MD_steps*dt)
  
    call dimer_io%init(hfile, 'dimer', colloids, H5MD_LINEAR, position_step=N_loop, position_time=N_MD_steps*dt)
  
    call PTkill(config)
    
  