def METHOD_NAME():
    # Instantiate the energy group data
    egroups = [1e-5, 0.0635, 10.0, 1.0e2, 1.0e3, 0.5e6, 1.0e6, 20.0e6]
    groups = openmc.mgxs.EnergyGroups(egroups)
    # Instantiate the 7-group (C5G7) cross section data
    uo2_xsdata = openmc.XSdata('UO2', groups, temperatures=[294.0, 600.0])
    uo2_xsdata.order = 0
    scatter_matrix = np.array([[
        [0.1275370, 0.0423780, 0.0000094, 0.0000000, 0.0000000, 0.0000000, 0.0000000],
        [0.0000000, 0.3244560, 0.0016314, 0.0000000, 0.0000000, 0.0000000, 0.0000000],
        [0.0000000, 0.0000000, 0.4509400, 0.0026792, 0.0000000, 0.0000000, 0.0000000],
        [0.0000000, 0.0000000, 0.0000000, 0.4525650, 0.0055664, 0.0000000, 0.0000000],
        [0.0000000, 0.0000000, 0.0000000, 0.0001253, 0.2714010, 0.0102550, 0.0000000],
        [0.0000000, 0.0000000, 0.0000000, 0.0000000, 0.0012968, 0.2658020, 0.0168090],
        [0.0000000, 0.0000000, 0.0000000, 0.0000000, 0.0000000, 0.0085458, 0.2730800]
    ]])
    scatter_matrix = np.rollaxis(scatter_matrix, 0, 3)
    # Original C5G7 data
    uo2_xsdata.set_total([0.1779492, 0.3298048, 0.4803882, 0.5543674, 0.3118013, 0.3951678, 0.5644058], temperature=294.0)
    uo2_xsdata.set_absorption([8.0248E-03, 3.7174E-03, 2.6769E-02, 9.6236E-02, 3.0020E-02, 1.1126E-01, 2.8278E-01], temperature=294.0)
    uo2_xsdata.set_scatter_matrix(scatter_matrix, temperature=294.0)
    uo2_xsdata.set_fission([7.21206E-03, 8.19301E-04, 6.45320E-03, 1.85648E-02, 1.78084E-02, 8.30348E-02, 2.16004E-01], temperature=294.0)
    uo2_xsdata.set_nu_fission([2.005998E-02, 2.027303E-03, 1.570599E-02, 4.518301E-02, 4.334208E-02, 2.020901E-01, 5.257105E-01], temperature=294.0)
    uo2_xsdata.set_chi([5.8791E-01, 4.1176E-01, 3.3906E-04, 1.1761E-07, 0.0000E+00, 0.0000E+00, 0.0000E+00], temperature=294.0)
    # Altered C5G7 data (permuted Chi)
    uo2_xsdata.set_total([0.1779492, 0.3298048, 0.4803882, 0.5543674, 0.3118013, 0.3951678, 0.5644058], temperature=600.0)
    uo2_xsdata.set_absorption([8.0248E-03, 3.7174E-03, 2.6769E-02, 9.6236E-02, 3.0020E-02, 1.1126E-01, 2.8278E-01], temperature=600.0)
    uo2_xsdata.set_scatter_matrix(scatter_matrix, temperature=600.0)
    uo2_xsdata.set_fission([7.21206E-03, 8.19301E-04, 6.45320E-03, 1.85648E-02, 1.78084E-02, 8.30348E-02, 2.16004E-01], temperature=600.0)
    uo2_xsdata.set_nu_fission([2.005998E-02, 2.027303E-03, 1.570599E-02, 4.518301E-02, 4.334208E-02, 2.020901E-01, 5.257105E-01], temperature=600.0)
    uo2_xsdata.set_chi([4.1176E-01, 5.8791E-01, 3.3906E-04, 1.1761E-07, 0.0000E+00, 0.0000E+00, 0.0000E+00], temperature=600.0)
    h2o_xsdata = openmc.XSdata('LWTR', groups)
    h2o_xsdata.order = 0
    h2o_xsdata.set_total([0.15920605, 0.412969593, 0.59030986, 0.58435,
                          0.718, 1.2544497, 2.650379])
    h2o_xsdata.set_absorption([6.0105E-04, 1.5793E-05, 3.3716E-04,
                               1.9406E-03, 5.7416E-03, 1.5001E-02,
                               3.7239E-02])
    scatter_matrix = np.array([[
        [0.0444777, 0.1134000, 0.0007235, 0.0000037, 0.0000001, 0.0000000, 0.0000000],
        [0.0000000, 0.2823340, 0.1299400, 0.0006234, 0.0000480, 0.0000074, 0.0000010],
        [0.0000000, 0.0000000, 0.3452560, 0.2245700, 0.0169990, 0.0026443, 0.0005034],
        [0.0000000, 0.0000000, 0.0000000, 0.0910284, 0.4155100, 0.0637320, 0.0121390],
        [0.0000000, 0.0000000, 0.0000000, 0.0000714, 0.1391380, 0.5118200, 0.0612290],
        [0.0000000, 0.0000000, 0.0000000, 0.0000000, 0.0022157, 0.6999130, 0.5373200],
        [0.0000000, 0.0000000, 0.0000000, 0.0000000, 0.0000000, 0.1324400, 2.4807000]
    ]])
    scatter_matrix = np.rollaxis(scatter_matrix, 0, 3)
    h2o_xsdata.set_scatter_matrix(scatter_matrix)
    mg_cross_sections_file = openmc.MGXSLibrary(groups)
    mg_cross_sections_file.add_xsdatas([uo2_xsdata, h2o_xsdata])
    mg_cross_sections_file.export_to_hdf5()