def test_gaussian_dipole_at_center(self):
x, y, z = [np.linspace(-5, 5, 51)] * 3
X, Y, Z = np.meshgrid(x, y, z, indexing='ij')
sigma = 1.5
rho = gaussian((X, Y, Z), (1, 0, 0), sigma) - gaussian(
(X, Y, Z), (-1, 0, 0), sigma)
mpe = MultipoleExpansion(charge_dist={
'discrete': False,
'rho': rho,
'xyz': (X, Y, Z)
},
l_max=3)
self.assertAlmostEqual(0, mpe.total_charge, places=4)
# dipole term for point charges obtained from hand calculation: q1,-1 = -sqrt(2), q10 = 0
# ==> phi_1(10e_x) = 0.02, but octupole also contributes to total phi!
phi_l = mpe.multipole_contribs((10, 0, 0))
np.testing.assert_array_almost_equal((0, 0.02, 0, 0), phi_l, decimal=3)
self.assertAlmostEqual(mpe.eval((10, 0, 0), 3),
1 / 9. - 1 / 11.,
places=3)
self.assertAlmostEqual(mpe(10, 0, 0), 1 / 9. - 1 / 11., places=3)
def test_gaussian_monopole_at_off_center(self):
x, y, z = [np.linspace(-5, 5, 51)] * 3
X, Y, Z = np.meshgrid(x, y, z, indexing='ij')
sigma = 1.5
rho = gaussian((X, Y, Z), (1, 0, 0), sigma)
mpe = MultipoleExpansion(charge_dist={
'discrete': False,
'rho': rho,
'xyz': (X, Y, Z)
},
l_max=2)
self.assertAlmostEqual(0.1,
mpe.multipole_contribs((11, 0, 0))[0],
places=4)
def test_charge_dist_without_charges_should_raise(self):
charge_dist = {
'discrete': True,
}
self.assertRaises(InvalidChargeDistributionException,
lambda: MultipoleExpansion(charge_dist, 2))
def test_charges_without_q_should_raise(self):
charge_dist = {
'discrete': False,
'charges': [{
'qa': 1,
'xyz': (1, 0, 0)
}],
}
self.assertRaises(InvalidChargeDistributionException,
lambda: MultipoleExpansion(charge_dist, 2))
def test_dipole_of_point_charges(self):
mpe = MultipoleExpansion(
{
'discrete':
True,
'charges': [
{
'q': 1,
'xyz': (1, 0, 0)
},
{
'q': -1,
'xyz': (-1, 0, 0)
},
]
},
l_max=3)
np.testing.assert_array_almost_equal((0, 0.02, 0, 0),
mpe.multipole_contribs(
(10, 0, 0)),
decimal=3)
def test_charge_dist_without_discrete_should_raise(self):
charge_dist = {
'charges': [
{
'q': 1,
'xyz': (1, 0, 0)
},
{
'q': -1,
'xyz': (-1, 0, 0)
},
]
}
self.assertRaises(InvalidChargeDistributionException,
lambda: MultipoleExpansion(charge_dist, 2))
def test_discrete_charge_dist_with_rho_should_raise(self):
charge_dist = {'discrete': True, 'rho': None, 'xyz': None}
self.assertRaises(InvalidChargeDistributionException,
lambda: MultipoleExpansion(charge_dist, 2))