def get_free_sphere_params(structure, rad_dict=None, probe_rad=0.1):
    """
    Analyze the void space in the input structure using voronoi decomposition
    Calls Zeo++ for Voronoi decomposition.

    Args:
        structure: pymatgen.core.structure.Structure
        rad_dict (optional): Dictionary of radii of elements in structure.
            If not given, Zeo++ default values are used.
            Note: Zeo++ uses atomic radii of elements.
            For ionic structures, pass rad_dict with ionic radii
        probe_rad (optional): Sampling probe radius in Angstroms. Default is
            0.1 A

    Returns:
        voronoi nodes as pymatgen.core.structure.Strucutre within the
        unit cell defined by the lattice of input structure
        voronoi face centers as pymatgen.core.structure.Strucutre within the
        unit cell defined by the lattice of input structure
    """

    with ScratchDir('.'):
        name = "temp_zeo1"
        zeo_inp_filename = name + ".cssr"
        ZeoCssr(structure).write_file(zeo_inp_filename)
        rad_file = None
        rad_flag = False

        if rad_dict:
            rad_file = name + ".rad"
            rad_flag = True
            with open(rad_file, 'w+') as fp:
                for el in rad_dict.keys():
                    fp.write("{} {}\n".format(el, rad_dict[el].real))

        atmnet = AtomNetwork.read_from_CSSR(
            zeo_inp_filename, rad_flag=rad_flag, rad_file=rad_file)
        out_file = "temp.res"
        atmnet.calculate_free_sphere_parameters(out_file)
        if os.path.isfile(out_file) and os.path.getsize(out_file) > 0:
            with open(out_file, "rt") as fp:
                output = fp.readline()
        else:
            output = ""
    fields = [val.strip() for val in output.split()][1:4]
    if len(fields) == 3:
        fields = [float(field) for field in fields]
        free_sphere_params = {'inc_sph_max_dia': fields[0],
                              'free_sph_max_dia': fields[1],
                              'inc_sph_along_free_sph_path_max_dia': fields[2]}
    return free_sphere_params