def test_linear_electric_potential(self):
E = np.array([1., 2., 3.])
phi0 = 4.
electric_field = constraints.LinearElectricPotential(E=E, phi0=phi0)
np.testing.assert_almost_equal(E, electric_field.E)
self.assertEqual(phi0, electric_field.phi0)
self.system.constraints.add(electric_field)
p = self.system.part.add(pos=[0.5, 0.5, 0.5])
if espressomd.has_features("ELECTROSTATICS"):
q_part = -3.1
p.q = q_part
else:
q_part = 0.0
self.system.integrator.run(0)
np.testing.assert_almost_equal(q_part * E, np.copy(p.f))
self.assertAlmostEqual(self.system.analysis.energy()['total'],
q_part * (- np.dot(E, p.pos) + phi0))
self.assertAlmostEqual(self.system.analysis.energy()['total'],
self.system.analysis.energy()['external_fields'])
def test_linear_electric_potential(self):
E = np.array([1., 2., 3.])
phi0 = 4.
electric_field = constraints.LinearElectricPotential(E=E, phi0=phi0)
np.testing.assert_almost_equal(E, electric_field.E)
self.assertEqual(phi0, electric_field.phi0)
self.system.constraints.add(electric_field)
p = self.system.part.add(pos=[0.5, 0.5, 0.5])
p.q = -3.1
self.system.integrator.run(0)
np.testing.assert_almost_equal(p.q * E, np.copy(p.f))
self.assertAlmostEqual(self.system.analysis.energy()['total'],
p.q * (- np.dot(E, p.pos) + phi0))
self.assertAlmostEqual(self.system.analysis.energy()['total'],
self.system.analysis.energy()['external_fields'])
np.testing.assert_allclose(
electric_field.call_method("_eval_field", x=[0, 0, 0]), phi0)
np.testing.assert_allclose(
electric_field.call_method("_eval_field", x=[3, 2, 1]),
np.dot(-E, [3, 2, 1]) + phi0)
np.testing.assert_allclose(
electric_field.call_method("_eval_jacobian", x=[3, 2, 1]), -E)