def test_mchange_onflip(self):
magnet = mod.Magnet(np.ones([ 2,2 ]))
dm = magnet.get_mchange_onflip(0,0)
self.assertEqual(dm, -2.)
magnet = mod.Magnet(-np.ones([ 2,2 ]))
dm = magnet.get_mchange_onflip(0,0)
self.assertEqual(dm, 2.)
def test_M_at_0(self):
np.random.seed(42)
thiss = np.random.randint(2, size=[4,4])*2-1
magnet = mod.Magnet(s=thiss)
mf = 1.
magnet, results = mod.termalize(magnet, nsteps = int(1e4), T = 0.1)
self.assertAlmostEqual(mf, results['MabsMEAN']/magnet.N, delta = 2e-3)
def test_M_at_inf(self):
np.random.seed(42)
thiss = np.random.randint(2, size=[4,4])*2 -1
magnet = mod.Magnet(s = thiss)
mf = 0
nsteps = 1e4
magnet, results = mod.termalize(magnet, nsteps = int(nsteps), T = 10)
self.assertAlmostEqual(mf/magnet.N, results['MabsMEAN']/magnet.N, delta = 0.26)
def test_echange_onflip(self):
for thiss in [np.ones([2,2]), -1*np.ones( [2,2]), np.ones([8,8])]:
magnet = mod.Magnet(s=thiss)
E = magnet.get_total_energy()
detest = magnet.get_total_echange_onflip(0,0)
magnet.flipthespin(0,0)
enew = magnet.get_total_energy()
self.assertEqual(detest, enew - E)
def test_e_at_inf(self):
"""
test if after termalization, the energy is as expected at low temperature (i e close to minimal)
"""
np.random.seed(42)
thiss = np.random.randint(2, size=[4,4])*2-1
magnet = mod.Magnet(s=thiss)
ef = 0.
nsteps = 1e4
magnet, results = mod.termalize(magnet, nsteps = int(nsteps), T = 8)
self.assertAlmostEqual(ef/magnet.N, results['EMEAN']/magnet.N, delta=0.25)
def test_exact_echange(self):
magnet = mod.Magnet(s = np.ones([2,2]) )
detest = magnet.get_total_echange_onflip(0,0)
self.assertEqual(detest , 8*magnet.J)
def test_echange_isnegative(self):
magnet = mod.Magnet(s = np.array([[-1,1], [1,1]]))
detest = magnet.get_total_echange_onflip(0,0)
self.assertTrue(detest < 0)
def test_energy_after_flip(self):
magnet = mod.Magnet(s=np.ones([2,2]))
magnet.flipthespin(0,0)
enew = magnet.get_total_energy()
self.assertEqual(enew, 0)
def test_flip_a_spin(self):
magnet = mod.Magnet(Nx=16, Ny=16)
spin44 = magnet.s[4,4]
magnet.flipthespin(4,4)
self.assertEqual(spin44, -1*magnet.s[4,4])
def test_magnetic_energy(self):
for thiss in [-1*np.ones([2,2]), np.ones( [2,2]), np.ones([8,8])]:
magnet = mod.Magnet(s=thiss)
energy = magnet.get_total_energy()
self.assertEqual(-2*magnet.J*magnet.N, energy)
def test_magnetized(self):
for thiss in [-1*np.ones([2,2]), np.ones( [2,2]), np.ones([8,8])]:
magnet = mod.Magnet(s=thiss)
moment = magnet.get_magnetic_moment()
self.assertEqual(abs(moment), magnet.N)
def test_shape_indicators(self):
magnet = mod.Magnet()
self.assertEqual(magnet.Nx, 2)
self.assertEqual(magnet.Ny, 2)
self.assertEqual(magnet.N, 4)
def test_has_spins(self):
magnet = mod.Magnet()
self.assertTrue(hasattr(magnet, 's'))