def test_length(self):
atms = ['H']
b = scattering.length(atms, 10)
np.testing.assert_array_almost_equal(b, -3.7390, 3)
atms = ['1H', '2H', '3H']
b = scattering.length(atms, 13)
np.testing.assert_array_almost_equal(
b.reshape(13, 3)[:, 0], -3.7406, 3)
np.testing.assert_array_almost_equal(b.reshape(13, 3)[:, 1], 6.671, 3)
np.testing.assert_array_almost_equal(b.reshape(13, 3)[:, 2], 4.792, 3)
def neutron_factors(self, Q, atm, ion, occupancy, T, g, phase_factor):
scattering_length = scattering.length(atm, Q.size)
factors = space.prefactors(scattering_length, phase_factor, occupancy)
magnetic_form_factor = magnetic.form(Q, ion, g)
magnetic_factors = space.prefactors(magnetic_form_factor, phase_factor,
occupancy)
return factors * T, magnetic_factors * T
def test_structural(self):
a, b, c, alpha, beta, gamma = 5, 6, 7, np.pi / 2, np.pi / 3, np.pi / 4
inv_constants = crystal.reciprocal(a, b, c, alpha, beta, gamma)
a_, b_, c_, alpha_, beta_, gamma_ = inv_constants
h_range, nh = [-5, 5], 11
k_range, nk = [-5, 5], 11
l_range, nl = [-5, 5], 11
nu, nv, nw, n_atm = 5, 5, 5, 3
u = np.array([0.2, 0.1, 0.3])
v = np.array([0.3, 0.4, 0.2])
w = np.array([0.4, 0.5, 0.1])
atm = np.array(['Fe', 'Mn', 'Co'])
occupancy = np.array([0.75, 0.5, 0.6])
U11 = np.array([0.5, 0.3, 0.1])
U22 = np.array([0.6, 0.4, 0.3])
U33 = np.array([0.4, 0.6, 0.2])
U23 = np.array([0.05, -0.03, -0.01])
U13 = np.array([-0.04, 0.02, 0.02])
U12 = np.array([0.03, -0.02, 0.01])
twins = np.eye(3).reshape(1, 3, 3)
variants = np.array([1.0])
W = np.eye(3)
A = crystal.cartesian(a, b, c, alpha, beta, gamma)
B = crystal.cartesian(a_, b_, c_, alpha_, beta_, gamma_)
R = crystal.cartesian_rotation(a, b, c, alpha, beta, gamma)
D = crystal.cartesian_displacement(a, b, c, alpha, beta, gamma)
ux, uy, uz = crystal.transform(u, v, w, A)
ix, iy, iz = space.cell(nu, nv, nw, A)
rx, ry, rz, atms = space.real(ux, uy, uz, ix, iy, iz, atm)
reduced_params = space.reduced(h_range, k_range, l_range, nh, nk, nl,
nu, nv, nw)
indices, reverses, symops, Nu, Nv, Nw = reduced_params
symop = symmetry.laue_id(symops)
I = monocrystal.structural(occupancy, U11, U22, U33, U23, U13, U12, ux,
uy, uz, atm, h_range, k_range, l_range,
indices, symop, W, B, R, D, twins, variants,
nh, nk, nl, nu, nv, nw, Nu, Nv, Nw)
hmin, hmax = h_range
kmin, kmax = k_range
lmin, lmax = l_range
h, k, l = np.meshgrid(np.arange(hmin, hmax + 1),
np.arange(kmin, kmax + 1),
np.arange(lmin, lmax + 1),
indexing='ij')
h, k, l = h.flatten(), k.flatten(), l.flatten()
Qh, Qk, Ql = crystal.vector(h, k, l, B)
Q = np.sqrt(Qh**2 + Qk**2 + Ql**2)
n_hkl = Q.size
phase_factor = np.exp(2j * np.pi *
(h[:, np.newaxis] * u + k[:, np.newaxis] * v +
l[:, np.newaxis] * w))
scattering_power = scattering.length(atm, n_hkl).reshape(n_hkl, n_atm)
T = np.exp(-2 * np.pi**2 *
(U11 * (h * a_)[:, np.newaxis]**2 + U22 *
(k * b_)[:, np.newaxis]**2 + U33 *
(l * c_)[:, np.newaxis]**2 + U23 *
(k * l * b_ * c_ * 2)[:, np.newaxis] + U13 *
(h * l * a_ * c_ * 2)[:, np.newaxis] + U12 *
(h * k * a_ * b_ * 2)[:, np.newaxis]))
factors = scattering_power * occupancy * T * phase_factor
F = factors.sum(axis=1)
I_ref = np.abs(F)**2 / (nu * nv * nw * n_atm)
np.testing.assert_array_almost_equal(I, I_ref)
def test_displacive(self):
a, b, c, alpha, beta, gamma = 5, 6, 7, np.pi / 2, np.pi / 3, np.pi / 4
inv_constants = crystal.reciprocal(a, b, c, alpha, beta, gamma)
a_, b_, c_, alpha_, beta_, gamma_ = inv_constants
h_range, nh = [-1, 1], 5
k_range, nk = [0, 2], 11
l_range, nl = [-1, 0], 5
nu, nv, nw, n_atm = 2, 5, 4, 2
u = np.array([0.2, 0.1])
v = np.array([0.3, 0.4])
w = np.array([0.4, 0.5])
atm = np.array(['Fe', 'Mn'])
occupancy = np.array([0.75, 0.5])
U11 = np.array([0.5, 0.3])
U22 = np.array([0.6, 0.4])
U33 = np.array([0.4, 0.6])
U23 = np.array([0.05, -0.03])
U13 = np.array([-0.04, 0.02])
U12 = np.array([0.03, -0.02])
twins = np.eye(3).reshape(1, 3, 3)
variants = np.array([1.0])
W = np.eye(3)
A = crystal.cartesian(a, b, c, alpha, beta, gamma)
B = crystal.cartesian(a_, b_, c_, alpha_, beta_, gamma_)
R = crystal.cartesian_rotation(a, b, c, alpha, beta, gamma)
U = np.row_stack((U11, U22, U33, U23, U13, U12))
Ux, Uy, Uz = displacive.expansion(nu, nv, nw, n_atm, value=U)
index_parameters = space.mapping(h_range, k_range, l_range, nh, nk, nl,
nu, nv, nw)
h, k, l, H, K, L, indices, inverses, operators = index_parameters
Qh, Qk, Ql = crystal.vector(h, k, l, B)
Qx, Qy, Qz = crystal.transform(Qh, Qk, Ql, R)
Qx_norm, Qy_norm, Qz_norm, Q = space.unit(Qx, Qy, Qz)
ux, uy, uz = crystal.transform(u, v, w, A)
ix, iy, iz = space.cell(nu, nv, nw, A)
rx, ry, rz, atms = space.real(ux, uy, uz, ix, iy, iz, atm)
phase_factor = scattering.phase(Qx, Qy, Qz, ux, uy, uz)
scattering_length = scattering.length(atm, Q.size)
p = 3
coeffs = displacive.coefficients(p)
H_nuc, K_nuc, L_nuc, cond = space.condition(H,
K,
L,
nu,
nv,
nw,
centering='P')
U_r = displacive.products(Ux, Uy, Uz, p)
Q_k = displacive.products(Qx, Qy, Qz, p)
U_k, i_dft = displacive.transform(U_r, H, K, L, nu, nv, nw, n_atm)
factors = space.prefactors(scattering_length, phase_factor, occupancy)
I_ref = displacive.intensity(U_k, Q_k, coeffs, cond, p, i_dft, factors)
reduced_params = space.reduced(h_range, k_range, l_range, nh, nk, nl,
nu, nv, nw)
indices, reverses, symops, Nu, Nv, Nw = reduced_params
symop = symmetry.laue_id(symops)
centering = 1
even, odd = displacive.indices(p)
I = monocrystal.displacive(U_r, coeffs, occupancy, ux, uy, uz, atm,
h_range, k_range, l_range, indices, symop,
W, B, R, twins, variants, nh, nk, nl, nu,
nv, nw, Nu, Nv, Nw, p, even, centering)
np.testing.assert_array_almost_equal(I, I_ref)
def test_occupational(self):
a, b, c, alpha, beta, gamma = 5, 6, 7, np.pi / 2, np.pi / 3, np.pi / 4
inv_constants = crystal.reciprocal(a, b, c, alpha, beta, gamma)
a_, b_, c_, alpha_, beta_, gamma_ = inv_constants
h_range, nh = [-1, 1], 5
k_range, nk = [0, 2], 11
l_range, nl = [-1, 0], 5
nu, nv, nw, n_atm = 2, 5, 4, 2
u = np.array([0.2, 0.1])
v = np.array([0.3, 0.4])
w = np.array([0.4, 0.5])
atm = np.array(['Fe', 'Mn'])
occupancy = np.array([0.75, 0.5])
U11 = np.array([0.5, 0.3])
U22 = np.array([0.6, 0.4])
U33 = np.array([0.4, 0.6])
U23 = np.array([0.05, -0.03])
U13 = np.array([-0.04, 0.02])
U12 = np.array([0.03, -0.02])
twins = np.eye(3).reshape(1, 3, 3)
variants = np.array([1.0])
W = np.eye(3)
T = space.debye_waller(h_range, k_range, l_range, nh, nk, nl, U11, U22,
U33, U23, U13, U12, a_, b_, c_)
A = crystal.cartesian(a, b, c, alpha, beta, gamma)
B = crystal.cartesian(a_, b_, c_, alpha_, beta_, gamma_)
R = crystal.cartesian_rotation(a, b, c, alpha, beta, gamma)
D = crystal.cartesian_displacement(a, b, c, alpha, beta, gamma)
A_r = occupational.composition(nu, nv, nw, n_atm, value=occupancy)
index_parameters = space.mapping(h_range, k_range, l_range, nh, nk, nl,
nu, nv, nw)
h, k, l, H, K, L, indices, inverses, operators = index_parameters
Qh, Qk, Ql = crystal.vector(h, k, l, B)
Qx, Qy, Qz = crystal.transform(Qh, Qk, Ql, R)
Qx_norm, Qy_norm, Qz_norm, Q = space.unit(Qx, Qy, Qz)
ux, uy, uz = crystal.transform(u, v, w, A)
ix, iy, iz = space.cell(nu, nv, nw, A)
rx, ry, rz, atms = space.real(ux, uy, uz, ix, iy, iz, atm)
phase_factor = scattering.phase(Qx, Qy, Qz, ux, uy, uz)
scattering_length = scattering.length(atm, Q.size)
A_k, i_dft = occupational.transform(A_r, H, K, L, nu, nv, nw, n_atm)
factors = space.prefactors(scattering_length, phase_factor, occupancy)
factors *= T
I_ref = occupational.intensity(A_k, i_dft, factors)
reduced_params = space.reduced(h_range, k_range, l_range, nh, nk, nl,
nu, nv, nw)
indices, reverses, symops, Nu, Nv, Nw = reduced_params
symop = symmetry.laue_id(symops)
I = monocrystal.occupational(A_r, occupancy, U11, U22, U33, U23, U13,
U12, ux, uy, uz, atm, h_range, k_range,
l_range, indices, symop, W, B, R, D,
twins, variants, nh, nk, nl, nu, nv, nw,
Nu, Nv, Nw)
np.testing.assert_array_almost_equal(I, I_ref)
def test_intensity(self):
a, b, c, alpha, beta, gamma = 5, 6, 7, np.pi / 2, np.pi / 3, np.pi / 4
inv_constants = crystal.reciprocal(a, b, c, alpha, beta, gamma)
a_, b_, c_, alpha_, beta_, gamma_ = inv_constants
h_range, nh = [-1, 1], 5
k_range, nk = [0, 2], 11
l_range, nl = [-1, 0], 5
nu, nv, nw, n_atm = 2, 5, 4, 2
u = np.array([0.2, 0.1])
v = np.array([0.3, 0.4])
w = np.array([0.4, 0.5])
atm = np.array(['Fe', 'Mn'])
occupancy = np.array([0.75, 0.5])
U11 = np.array([0.5, 0.3])
U22 = np.array([0.6, 0.4])
U33 = np.array([0.4, 0.6])
U23 = np.array([0.05, -0.03])
U13 = np.array([-0.04, 0.02])
U12 = np.array([0.03, -0.02])
T = space.debye_waller(h_range, k_range, l_range, nh, nk, nl, U11, U22,
U33, U23, U13, U12, a_, b_, c_)
A = crystal.cartesian(a, b, c, alpha, beta, gamma)
B = crystal.cartesian(a_, b_, c_, alpha_, beta_, gamma_)
R = crystal.cartesian_rotation(a, b, c, alpha, beta, gamma)
A_r = occupational.composition(nu, nv, nw, n_atm, value=occupancy)
index_parameters = space.mapping(h_range, k_range, l_range, nh, nk, nl,
nu, nv, nw)
h, k, l, H, K, L, indices, inverses, operators = index_parameters
Qh, Qk, Ql = crystal.vector(h, k, l, B)
Qx, Qy, Qz = crystal.transform(Qh, Qk, Ql, R)
Qx_norm, Qy_norm, Qz_norm, Q = space.unit(Qx, Qy, Qz)
ux, uy, uz = crystal.transform(u, v, w, A)
ix, iy, iz = space.cell(nu, nv, nw, A)
rx, ry, rz, atms = space.real(ux, uy, uz, ix, iy, iz, atm)
phase_factor = scattering.phase(Qx, Qy, Qz, ux, uy, uz)
scattering_length = scattering.length(atm, Q.size)
A_k, i_dft = occupational.transform(A_r, H, K, L, nu, nv, nw, n_atm)
factors = space.prefactors(scattering_length, phase_factor, occupancy)
factors *= T
I = occupational.intensity(A_k, i_dft, factors)
n_hkl = Q.size
n_xyz = nu * nv * nw * n_atm
i, j = np.triu_indices(n_xyz, 1)
k, l = np.mod(i, n_atm), np.mod(j, n_atm)
m = np.arange(n_xyz)
n = np.mod(m, n_atm)
rx_ij = rx[j] - rx[i]
ry_ij = ry[j] - ry[i]
rz_ij = rz[j] - rz[i]
bc = scattering.length(atm, 1)
T = T.reshape(n_hkl, n_atm)
A_i, A_j, A_m = A_r[i], A_r[j], A_r[m]
c_k, c_l, c_n = occupancy[k], occupancy[l], occupancy[n]
b_k, b_l, b_n = bc[k], bc[l], bc[n]
T_k, T_l, T_n = T[:, k], T[:, l], T[:, n]
I_ref = ((c_n**2*(b_n*b_n.conj()).real*A_m**2*T_n**2).sum(axis=1)\
+ 2*(c_k*c_l*(b_k*b_l.conj()).real*A_i*A_j*T_k*T_l*\
np.cos(Qx[:,np.newaxis]*rx_ij+\
Qy[:,np.newaxis]*ry_ij+\
Qz[:,np.newaxis]*rz_ij)).sum(axis=1))/n_xyz
np.testing.assert_array_almost_equal(I, I_ref)
def test_structure(self):
a, b, c, alpha, beta, gamma = 5, 6, 7, np.pi / 2, np.pi / 3, np.pi / 4
inv_constants = crystal.reciprocal(a, b, c, alpha, beta, gamma)
a_, b_, c_, alpha_, beta_, gamma_ = inv_constants
h_range, nh = [-1, 1], 5
k_range, nk = [0, 2], 11
l_range, nl = [-1, 0], 5
nu, nv, nw, n_atm = 2, 5, 4, 2
u = np.array([0.2, 0.1])
v = np.array([0.3, 0.4])
w = np.array([0.4, 0.5])
atm = np.array(['Fe', 'Mn'])
occupancy = np.array([0.75, 0.5])
U11 = np.array([0.5, 0.3])
U22 = np.array([0.6, 0.4])
U33 = np.array([0.4, 0.6])
U23 = np.array([0.05, -0.03])
U13 = np.array([-0.04, 0.02])
U12 = np.array([0.03, -0.02])
T = space.debye_waller(h_range, k_range, l_range, nh, nk, nl, U11, U22,
U33, U23, U13, U12, a_, b_, c_)
A = crystal.cartesian(a, b, c, alpha, beta, gamma)
B = crystal.cartesian(a_, b_, c_, alpha_, beta_, gamma_)
R = crystal.cartesian_rotation(a, b, c, alpha, beta, gamma)
A_r = occupational.composition(nu, nv, nw, n_atm, value=occupancy)
index_parameters = space.mapping(h_range, k_range, l_range, nh, nk, nl,
nu, nv, nw)
h, k, l, H, K, L, indices, inverses, operators = index_parameters
Qh, Qk, Ql = crystal.vector(h, k, l, B)
Qx, Qy, Qz = crystal.transform(Qh, Qk, Ql, R)
Qx_norm, Qy_norm, Qz_norm, Q = space.unit(Qx, Qy, Qz)
ux, uy, uz = crystal.transform(u, v, w, A)
ix, iy, iz = space.cell(nu, nv, nw, A)
rx, ry, rz, atms = space.real(ux, uy, uz, ix, iy, iz, atm)
phase_factor = scattering.phase(Qx, Qy, Qz, ux, uy, uz)
scattering_length = scattering.length(atm, Q.size)
A_k, i_dft = occupational.transform(A_r, H, K, L, nu, nv, nw, n_atm)
factors = space.prefactors(scattering_length, phase_factor, occupancy)
factors *= T
F, prod = occupational.structure(A_k, i_dft, factors)
n_hkl = Q.size
n_xyz = nu * nv * nw * n_atm
m = np.arange(n_xyz)
n = np.mod(m, n_atm)
rx_m = rx[m]
ry_m = ry[m]
rz_m = rz[m]
bc = scattering.length(atm, 1)
T = T.reshape(n_hkl, n_atm)
A_m = A_r[m]
c_n = occupancy[n]
b_n = bc[n]
T_n = T[:, n]
prod_ref = (c_n*b_n*A_m*T_n*np.exp(1j*(Qx[:,np.newaxis]*rx_m+\
Qy[:,np.newaxis]*ry_m+\
Qz[:,np.newaxis]*rz_m)))
F_ref = prod_ref.sum(axis=1)
prod_ref = prod_ref.reshape(n_hkl, nu * nv * nw,
n_atm).sum(axis=1).flatten()
np.testing.assert_array_almost_equal(F, F_ref)
np.testing.assert_array_almost_equal(prod, prod_ref)
def test_structure(self):
a, b, c, alpha, beta, gamma = 5, 6, 7, np.pi / 2, np.pi / 3, np.pi / 4
inv_constants = crystal.reciprocal(a, b, c, alpha, beta, gamma)
a_, b_, c_, alpha_, beta_, gamma_ = inv_constants
h_range, nh = [-1, 1], 5
k_range, nk = [0, 2], 11
l_range, nl = [-1, 0], 5
nu, nv, nw, n_atm = 2, 5, 4, 2
u = np.array([0.2, 0.1])
v = np.array([0.3, 0.4])
w = np.array([0.4, 0.5])
atm = np.array(['Fe', 'Mn'])
occupancy = np.array([0.75, 0.5])
U11 = np.array([0.5, 0.3])
U22 = np.array([0.6, 0.4])
U33 = np.array([0.4, 0.6])
U23 = np.array([0.05, -0.03])
U13 = np.array([-0.04, 0.02])
U12 = np.array([0.03, -0.02])
A = crystal.cartesian(a, b, c, alpha, beta, gamma)
B = crystal.cartesian(a_, b_, c_, alpha_, beta_, gamma_)
R = crystal.cartesian_rotation(a, b, c, alpha, beta, gamma)
U = np.row_stack((U11, U22, U33, U23, U13, U12))
Ux, Uy, Uz = displacive.expansion(nu, nv, nw, n_atm, value=U)
index_parameters = space.mapping(h_range, k_range, l_range, nh, nk, nl,
nu, nv, nw)
h, k, l, H, K, L, indices, inverses, operators = index_parameters
Qh, Qk, Ql = crystal.vector(h, k, l, B)
Qx, Qy, Qz = crystal.transform(Qh, Qk, Ql, R)
Qx_norm, Qy_norm, Qz_norm, Q = space.unit(Qx, Qy, Qz)
ux, uy, uz = crystal.transform(u, v, w, A)
ix, iy, iz = space.cell(nu, nv, nw, A)
rx, ry, rz, atms = space.real(ux, uy, uz, ix, iy, iz, atm)
phase_factor = scattering.phase(Qx, Qy, Qz, ux, uy, uz)
scattering_length = scattering.length(atm, Q.size)
p = 3
coeffs = displacive.coefficients(p)
H_nuc, K_nuc, L_nuc, cond = space.condition(H, K, L, nu, nv, nw)
U_r = displacive.products(Ux, Uy, Uz, p)
Q_k = displacive.products(Qx, Qy, Qz, p)
U_k, i_dft = displacive.transform(U_r, H, K, L, nu, nv, nw, n_atm)
factors = space.prefactors(scattering_length, phase_factor, occupancy)
F, F_nuc, \
prod, prod_nuc, \
V_k, V_k_nuc, \
even, bragg = displacive.structure(U_k, Q_k, coeffs, cond,
p, i_dft, factors)
n_hkl = Q.size
n_xyz = nu * nv * nw * n_atm
m = np.arange(n_xyz)
n = np.mod(m, n_atm)
rx_m = rx[m]
ry_m = ry[m]
rz_m = rz[m]
bc = scattering.length(atm, 1)
U_r = U_r.reshape(coeffs.shape[0], n_xyz)
Q_k = Q_k.reshape(coeffs.shape[0], n_hkl)
U_m = U_r[:, m]
c_n = occupancy[n]
b_n = bc[n]
exp_iQ_dot_U_m = np.dot(coeffs * U_m.T, Q_k).T
prod_ref = c_n*b_n*exp_iQ_dot_U_m*np.exp(1j*(Qx[:,np.newaxis]*rx_m+\
Qy[:,np.newaxis]*ry_m+\
Qz[:,np.newaxis]*rz_m))
F_ref = prod_ref.sum(axis=1)
prod_ref = prod_ref.reshape(n_hkl, nu * nv * nw,
n_atm).sum(axis=1).flatten()
np.testing.assert_array_almost_equal(F, F_ref)
np.testing.assert_array_almost_equal(prod, prod_ref)
cos_iQ_dot_U_m = np.dot((coeffs * U_m.T)[:, even], Q_k[even, :]).T
prod_nuc_ref = c_n*b_n*cos_iQ_dot_U_m*\
np.exp(1j*(Qx[:,np.newaxis]*rx_m+\
Qy[:,np.newaxis]*ry_m+\
Qz[:,np.newaxis]*rz_m))
F_nuc_ref = prod_nuc_ref.sum(axis=1)[cond]
prod_nuc_ref = prod_nuc_ref.reshape(n_hkl, nu * nv * nw,
n_atm).sum(axis=1)[cond].flatten()
np.testing.assert_array_almost_equal(F_nuc, F_nuc_ref)
np.testing.assert_array_almost_equal(prod_nuc, prod_nuc_ref)
factors = (c_n * b_n * cos_iQ_dot_U_m).flatten()
F_nuc_ref = space.bragg(Qx, Qy, Qz, rx, ry, rz, factors, cond)
np.testing.assert_array_almost_equal(F_nuc, F_nuc_ref)
def test_intensity(self):
a, b, c, alpha, beta, gamma = 5, 6, 7, np.pi / 2, np.pi / 3, np.pi / 4
inv_constants = crystal.reciprocal(a, b, c, alpha, beta, gamma)
a_, b_, c_, alpha_, beta_, gamma_ = inv_constants
h_range, nh = [-1, 1], 5
k_range, nk = [0, 2], 11
l_range, nl = [-1, 0], 5
nu, nv, nw, n_atm = 2, 5, 4, 2
u = np.array([0.2, 0.1])
v = np.array([0.3, 0.4])
w = np.array([0.4, 0.5])
atm = np.array(['Fe', 'Mn'])
occupancy = np.array([0.75, 0.5])
U11 = np.array([0.5, 0.3])
U22 = np.array([0.6, 0.4])
U33 = np.array([0.4, 0.6])
U23 = np.array([0.05, -0.03])
U13 = np.array([-0.04, 0.02])
U12 = np.array([0.03, -0.02])
A = crystal.cartesian(a, b, c, alpha, beta, gamma)
B = crystal.cartesian(a_, b_, c_, alpha_, beta_, gamma_)
R = crystal.cartesian_rotation(a, b, c, alpha, beta, gamma)
U = np.row_stack((U11, U22, U33, U23, U13, U12))
Ux, Uy, Uz = displacive.expansion(nu, nv, nw, n_atm, value=U)
index_parameters = space.mapping(h_range, k_range, l_range, nh, nk, nl,
nu, nv, nw)
h, k, l, H, K, L, indices, inverses, operators = index_parameters
Qh, Qk, Ql = crystal.vector(h, k, l, B)
Qx, Qy, Qz = crystal.transform(Qh, Qk, Ql, R)
Qx_norm, Qy_norm, Qz_norm, Q = space.unit(Qx, Qy, Qz)
ux, uy, uz = crystal.transform(u, v, w, A)
ix, iy, iz = space.cell(nu, nv, nw, A)
rx, ry, rz, atms = space.real(ux, uy, uz, ix, iy, iz, atm)
phase_factor = scattering.phase(Qx, Qy, Qz, ux, uy, uz)
scattering_length = scattering.length(atm, Q.size)
p = 3
coeffs = displacive.coefficients(p)
H_nuc, K_nuc, L_nuc, cond = space.condition(H,
K,
L,
nu,
nv,
nw,
centering='P')
U_r = displacive.products(Ux, Uy, Uz, p)
Q_k = displacive.products(Qx, Qy, Qz, p)
U_k, i_dft = displacive.transform(U_r, H, K, L, nu, nv, nw, n_atm)
factors = space.prefactors(scattering_length, phase_factor, occupancy)
# I = displacive.intensity(U_k, Q_k, coeffs, cond, p, i_dft, factors)
I, F_nuc = displacive.intensity(U_k,
Q_k,
coeffs,
cond,
p,
i_dft,
factors,
subtract=False)
n_hkl = Q.size
n_xyz = nu * nv * nw * n_atm
i, j = np.triu_indices(n_xyz, 1)
k, l = np.mod(i, n_atm), np.mod(j, n_atm)
m = np.arange(n_xyz)
n = np.mod(m, n_atm)
rx_ij = rx[j] - rx[i]
ry_ij = ry[j] - ry[i]
rz_ij = rz[j] - rz[i]
bc = scattering.length(atm, 1)
U_r = U_r.reshape(coeffs.shape[0], n_xyz)
Q_k = Q_k.reshape(coeffs.shape[0], n_hkl)
U_i, U_j, U_m = U_r[:, i], U_r[:, j], U_r[:, m]
c_k, c_l, c_n = occupancy[k], occupancy[l], occupancy[n]
b_k, b_l, b_n = bc[k], bc[l], bc[n]
exp_iQ_dot_U_m = np.dot(coeffs * U_m.T, Q_k).T
exp_iQ_dot_U_i = np.dot(coeffs * U_i.T, Q_k).T
exp_iQ_dot_U_j = np.dot(coeffs * U_j.T, Q_k).T
I_ref = ((c_n**2*(b_n*b_n.conj()).real*\
(exp_iQ_dot_U_m*exp_iQ_dot_U_m.conj()).real).sum(axis=1)\
+ 2*(c_k*c_l*(b_k*b_l.conj()).real*
((exp_iQ_dot_U_i*exp_iQ_dot_U_j.conj()*\
np.cos(Qx[:,np.newaxis]*rx_ij+\
Qy[:,np.newaxis]*ry_ij+\
Qz[:,np.newaxis]*rz_ij)).real+
(exp_iQ_dot_U_i*exp_iQ_dot_U_j.conj()*\
np.sin(Qx[:,np.newaxis]*rx_ij+\
Qy[:,np.newaxis]*ry_ij+\
Qz[:,np.newaxis]*rz_ij)).imag)).sum(axis=1))/n_xyz
np.testing.assert_array_almost_equal(I, I_ref)
