def testForce(self): lj = LennardJones(epsilon=2.0, sigma=2.0) # force in the minimum self.assertAlmostEqual( (lj.computeForce(2.0 * 2.0**(1.0 / 6.0), 0.0, 0.0) - Real3D(0.0, 0.0, 0.0)).sqr(), 0)