def test_scattering_vector(self):
Fe_fcc = Lattice.face_centered_cubic(0.287) # FCC iron
hkl = HklPlane(2, 0, 0, Fe_fcc)
Gc = hkl.scattering_vector()
self.assertAlmostEqual(np.linalg.norm(Gc),
1 / hkl.interplanar_spacing())
Al_fcc = Lattice.face_centered_cubic(0.405)
hkl = HklPlane(0, 0, 2, lattice=Al_fcc)
Gc = hkl.scattering_vector()
self.assertAlmostEqual(np.linalg.norm(Gc),
1 / hkl.interplanar_spacing())
def test_110_normal_monoclinic(self):
"""Testing (110) plane normal in monoclinic crystal structure.
This test comes from
http://www.mse.mtu.edu/~drjohn/my3200/stereo/sg5.html
corrected for a few errors in the html page.
In this test, the lattice is defined with the c-axis aligned with the Z direction of the Cartesian frame.
"""
Mg2Si = Lattice.from_parameters(1.534,
0.405,
0.683,
90.,
106.,
90.,
x_aligned_with_a=False)
a = Mg2Si.matrix[0]
b = Mg2Si.matrix[1]
c = Mg2Si.matrix[2]
self.assertAlmostEqual(a[0], 1.475, 3)
self.assertAlmostEqual(a[1], 0., 3)
self.assertAlmostEqual(a[2], -0.423, 3)
self.assertAlmostEqual(b[0], 0., 3)
self.assertAlmostEqual(b[1], 0.405, 3)
self.assertAlmostEqual(b[2], 0., 3)
self.assertAlmostEqual(c[0], 0., 3)
self.assertAlmostEqual(c[1], 0., 3)
self.assertAlmostEqual(c[2], 0.683, 3)
p = HklPlane(1, 1, 1, Mg2Si)
Gc = p.scattering_vector()
self.assertAlmostEqual(Gc[0], 1.098, 3)
self.assertAlmostEqual(Gc[1], 2.469, 3)
self.assertAlmostEqual(Gc[2], 1.464, 3)
self.assertAlmostEqual(p.interplanar_spacing(), 0.325, 3)
Ghkl = np.dot(Mg2Si.matrix, Gc)
self.assertEqual(Ghkl[0], 1.) # h
self.assertEqual(Ghkl[1], 1.) # k
self.assertEqual(Ghkl[2], 1.) # l
