def METHOD_NAME():
    global h2o, hf_scanner, casscf_scanner
    h2o = gto.M(verbose=3,
                output='/dev/null',
                atom=[['O', 0, 0, 0], ['H', 0, -0.757, 0.587],
                      ['H', 0, 0.757, 0.587]],
                basis='def2-svp')
    hf_scanner = scf.RHF(h2o)
    hf_scanner.build()
    hf_scanner.conv_tol_grad = 1e-6
    hf_scanner.max_cycle = 700
    ethylene = gto.M(verbose=3,
                     output='/dev/null',
                     atom=''' C -0.0110224 -0.01183 -0.0271398
        C -0.000902273 0.0348566 1.34708
        H 1.07646 0.0030022 -0.456854
        H 0.976273 -0.140089 1.93039
        H -0.926855 -0.147441 1.98255
        H -0.983897 0.0103535 -0.538589
        ''',
                     unit='ANG',
                     basis='ccpvdz',
                     spin=0)
    hf = ethylene.RHF().run()
    ncas, nelecas = (2, 2)
    casscf_scanner = hf.CASSCF(ncas, nelecas)
    casscf_scanner.conv_tol = 1e-12
    casscf_scanner.conv_tol_grad = 1e-6