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)
def testEnergy(self):
lj=LennardJones(epsilon=2.0, sigma=2.0)
# root
self.assertAlmostEqual(lj.computeEnergy(2.0), 0.0)
self.assertAlmostEqual(lj.computeEnergy(2.0, 0.0, 0.0), 0.0)
# minimum
self.assertAlmostEqual(
lj.computeEnergy(2.0*2.0**(1.0/6.0)), -2.0)
self.assertAlmostEqual(lj.computeEnergy(0.0, 2.0*2.0**(1.0/6.0), 0.0), -2.0)
def testProperties(self) :
lj=LennardJones()
lj.epsilon=2.0
lj.sigma=2.0
lj.cutoff=4.0
lj.shift=0.0
# here we test energy computation, as testing property access
# would always work
self.assertAlmostEqual(lj.computeEnergy(2.0), 0.0)
self.assertAlmostEqual(lj.computeEnergy(2.0*2.0**(1.0/6.0)), -2.0)
