def _get_greensf_group_name(hdffile):
    """
    Return the name of the group containing the Green's function elements

    :param hdffile: h5py.File of the greensf.hdf file

    :returns: str of the group name containing the Green's Function elements
    """
    if '/GreensFunctionElements' in hdffile:
        return 'GreensFunctionElements'
    elif '/Hubbard1Elements' in hdffile:
        return 'Hubbard1Elements'