anchor.diff:  
     call axial_cf%init(block_length, N_loop, N_loop*N_MD_steps)
   
  -  call colloids%init_from_file(data_filename, 'janus', H5MD_FIXED)
  +  call colloids%init_from_file(data_filename, data_group, H5MD_FIXED)
   
     call input_data_file%open(data_filename, H5F_ACC_RDONLY_F)
  -  call h5oopen_f(input_data_file%particles, 'janus/position', pos_dset, error)
  -  call h5md_read_attribute(pos_dset, 'alpha', alpha)
  -  call h5md_read_attribute(pos_dset, 'beta', beta)
  -  call h5md_read_attribute(pos_dset, 'z0', z0)
  -  call h5oclose_f(pos_dset, error)
  +
  +  call h5aexists_by_name_f(input_data_file%particles, trim(data_group)//'/position', 'alpha', attr_exists, error)
  +  ! If the parameters alpha,beta,gamma are present, read them
  +  ! Only alpha is checked, if someone puts in alpha and not the rest, long hdf5 error log will show
  +  if (attr_exists) then
  +     call h5oopen_f(input_data_file%particles, trim(data_group)//'/position', pos_dset, error)
  +     call h5md_read_attribute(pos_dset, 'alpha', alpha)
  +     call h5md_read_attribute(pos_dset, 'beta', beta)
  +     call h5md_read_attribute(pos_dset, 'z0', z0)
  +     call h5oclose_f(pos_dset, error)
  +  end if
  +
     call input_data_file%close()
   
     colloids%image = 0
  
positive.code:   type(args_t) :: args
    character(len=144) :: data_filename
    character(len=144) :: links_file
  
    args = get_input_args()
    call PTparse(config, args%input_file, 11)
  
negative.code:   call solvent% init(N, N_species, system_name='solvent') !there will be 2 species of solvent particles
  
    data_filename = PTread_s(config, 'data_filename', loc=params_group)
    data_group = PTread_s(config, 'data_group', loc=params_group)
    link_treshold = PTread_d(config, 'link_treshold', loc=params_group)
    do_read_links = PTread_l(config, 'do_read_links', loc=params_group)
    if (do_read_links) links_file = PTread_s(config, 'links_file', loc=params_group)
  