anchor.diff:    colloids% pos(1,2) = colloids% pos(1,1) + d
     colloids% pos(2,:) = solvent_cells% edges(2)/2.d0 + 1.5d0*sigma_C
     
  -  write(*, *) colloids% pos  
  +  call h5gcreate_f(dimer_io%group, 'box', box_group, error)
  +  call h5md_write_attribute(box_group, 'dimension', 3)
  +  call dummy_element%create_fixed(box_group, 'edges', solvent_cells%edges)
  +  call h5gclose_f(box_group, error)
  +
  +  call h5gcreate_f(solvent_io%group, 'box', box_group, error)
  +  call h5md_write_attribute(box_group, 'dimension', 3)
  +  call dummy_element%create_fixed(box_group, 'edges', solvent_cells%edges)
  +  call h5gclose_f(box_group, error)
   
     call solvent% random_placement(solvent_cells% edges, colloids, solvent_colloid_lj)
   
  
positive.code:           sum(solvent% vel**2)/2
       call thermo_data%append(hfile, temperature, e1+e2+e_wall, kin_e, e1+e2+e_wall+kin_e)
  
       if (i .gt. 2000) then
          fixed = .false.
       end if
  
negative.code: 
    call PTkill(config)
  
    dimer_io%force_info%store = .false.
    dimer_io%id_info%store = .false.
    dimer_io%position_info%store = .true.
    dimer_io%position_info%mode = ior(H5MD_LINEAR,H5MD_STORE_TIME)
    dimer_io%position_info%step = N_MD_steps
    dimer_io%position_info%time = N_MD_steps*dt
    dimer_io%image_info%store = .true.
    dimer_io%image_info%mode = ior(H5MD_LINEAR,H5MD_STORE_TIME)
    dimer_io%image_info%step = N_MD_steps
    dimer_io%image_info%time = N_MD_steps*dt
    dimer_io%velocity_info%store = .true.
    dimer_io%velocity_info%mode = ior(H5MD_LINEAR,H5MD_STORE_TIME)
    dimer_io%velocity_info%step = N_MD_steps
    dimer_io%velocity_info%time = N_MD_steps*dt
    dimer_io%species_info%store = .true.
    dimer_io%species_info%mode = H5MD_FIXED
    call dimer_io%init(hfile, 'dimer', colloids)
  
    solvent_io%force_info%store = .false.
    solvent_io%id_info%store = .false.
    solvent_io%position_info%store = .true.
    solvent_io%position_info%mode = ior(H5MD_LINEAR,H5MD_STORE_TIME)
    solvent_io%position_info%step = N_loop*N_MD_steps
    solvent_io%position_info%time = N_loop*N_MD_steps*dt
    solvent_io%image_info%store = .true.
    solvent_io%image_info%mode = ior(H5MD_LINEAR,H5MD_STORE_TIME)
    solvent_io%image_info%step = N_loop*N_MD_steps
    solvent_io%image_info%time = N_loop*N_MD_steps*dt
    solvent_io%velocity_info%store = .true.
    solvent_io%velocity_info%mode = ior(H5MD_LINEAR,H5MD_STORE_TIME)
    solvent_io%velocity_info%step = N_loop*N_MD_steps
    solvent_io%velocity_info%time = N_loop*N_MD_steps*dt
    solvent_io%species_info%store = .true.
    solvent_io%species_info%mode = ior(H5MD_LINEAR,H5MD_STORE_TIME)
    solvent_io%species_info%step = N_loop*N_MD_steps
    solvent_io%species_info%time = N_loop*N_MD_steps*dt
    call solvent_io%init(hfile, 'solvent', solvent)
  
    open(17,file ='dimerdata_FullExp_1.txt')
    open(19,file ='dimerdata_vx_flow_wall.txt')  
  
    colloids% species(1) = 1
  