def compute_field(mesh, nx=1, ny=1, m0=(1, 0, 0), pbc=None):
Ms = 1e6
sim = Simulation(mesh, Ms, unit_length=1e-9, name='dy', pbc=pbc)
sim.set_m(m0)
parameters = {
'absolute_tolerance': 1e-10,
'relative_tolerance': 1e-10,
'maximum_iterations': int(1e5)
}
demag = Demag(macrogeometry=MacroGeometry(nx=nx, ny=ny))
demag.parameters['phi_1'] = parameters
demag.parameters['phi_2'] = parameters
sim.add(demag)
field = sim.llg.effective_field.get_dolfin_function('Demag')
# XXX TODO: Would be good to compare all the field values, not
# just the value at a single point! (Max, 25.7.2014)
return field(0, 0, 0) / Ms
def test_thin_film_demag_against_real_demag():
sim = Sim(
df.BoxMesh(df.Point(0, 0, 0), df.Point(500e-9, 500e-9, 1e-9), 50, 50,
1), Ms)
sim.set_m((0, 0, 1))
tfdemag = ThinFilmDemag()
sim.add(tfdemag)
H_tfdemag = tfdemag.compute_field().view().reshape((3, -1)).mean(1)
demag = Demag()
sim.add(demag)
H_demag = demag.compute_field().view().reshape((3, -1)).mean(1)
diff = np.abs(H_tfdemag - H_demag) / Ms
print "Standard Demag:\n", H_demag
print "ThinFilmDemag:\n", H_tfdemag
print "Difference relative to Ms:\n", diff
assert np.allclose(H_tfdemag, H_demag, atol=0.05 * Ms) # 5% of Ms
sim.set_m((1, 0, 0))
H_tfdemag = tfdemag.compute_field().view().reshape((3, -1)).mean(1)
H_demag = demag.compute_field().view().reshape((3, -1)).mean(1)
print "Running again, changed m in the meantime."
diff = np.abs(H_tfdemag - H_demag) / Ms
print "Standard Demag:\n", H_demag
print "ThinFilmDemag:\n", H_tfdemag
print "Difference relative to Ms:\n", diff
assert np.allclose(H_tfdemag, H_demag, atol=0.005 * Ms) # 0.5% of Ms
def ring_down(m0=(1, 0.01, 0), pbc=None):
n = 49
assert n >= 1 and n % 2 == 1
Ms = 8.6e5
sim = Simulation(mesh, Ms, unit_length=1e-9, name='dy', pbc='1d')
sim.alpha = 1e-3
sim.set_m(m0)
sim.set_tol(1e-8, 1e-8)
parameters = {
'absolute_tolerance': 1e-10,
'relative_tolerance': 1e-10,
'maximum_iterations': int(1e5)
}
Ts = []
for i in range(-n / 2 + 1, n / 2 + 1):
Ts.append((10. * i, 0, 0))
demag = Demag(Ts=Ts)
demag.parameters['phi_1'] = parameters
demag.parameters['phi_2'] = parameters
sim.add(demag)
sim.add(Exchange(1.3e-11))
sim.schedule('save_ndt', every=2e-12)
sim.run_until(4e-9)
def relax_system():
Ms = 8.6e5
sim = Simulation(mesh, Ms, unit_length=1e-9, name = 'dy')
sim.alpha = 0.001
sim.set_m(np.load('m_000088.npy'))
#sim.set_tol(1e-6, 1e-6)
A = 1.3e-11
sim.add(Exchange(A))
parameters = {
'absolute_tolerance': 1e-10,
'relative_tolerance': 1e-10,
'maximum_iterations': int(1e5)
}
demag = Demag()
demag.parameters['phi_1'] = parameters
demag.parameters['phi_2'] = parameters
print demag.parameters
sim.add(demag)
sim.schedule('save_ndt', every=2e-12)
sim.schedule('save_vtk', every=2e-12, filename='vtks/m.pvd')
sim.schedule('save_m', every=2e-12, filename='npys/m.pvd')
sim.run_until(1e-9)
def run_finmag(demagsolver):
"""Run the finmag simulation and store data in (demagsolvertype)averages.txt."""
sim = Sim(mesh, Ms, unit_length=unit_length)
sim.alpha = 0.5
sim.set_m((1, 0, 1))
exchange = Exchange(13.0e-12)
sim.add(exchange)
demag = Demag(solver=demagsolver)
sim.add(demag)
fh = open(os.path.join(MODULE_DIR, demagsolver + "averages.txt"), "w")
fe = open(os.path.join(MODULE_DIR, demagsolver + "energies.txt"), "w")
# Progressbar
bar = pb.ProgressBar(maxval=60, \
widgets=[pb.ETA(), pb.Bar('=', '[', ']'), ' ', pb.Percentage()])
logger.info("Time integration")
times = np.linspace(0, 3.0e-10, 61)
#times = np.linspace(0, 3.0e-10, 100000)
for counter, t in enumerate(times):
bar.update(counter)
# Integrate
sim.run_until(t)
print counter
print("press return to continue")
_ = raw_input()
# Save averages to file
mx, my, mz = sim.m_average
fh.write(str(t) + " " + str(mx) + " " + str(my) + " " + str(mz) + "\n")
# Energies
E_e = exchange.compute_energy()
E_d = demag.compute_energy()
fe.write(str(E_e) + " " + str(E_d) + "\n")
# Energy densities
if counter == 10:
exch_energy = exchange.energy_density_function()
demag_energy = demag.demag.energy_density_function()
finmag_exch, finmag_demag = [], []
R = range(100)
for i in R:
finmag_exch.append(exch_energy([15, 15, i]))
finmag_demag.append(demag_energy([15, 15, i]))
# Store data
np.save(
os.path.join(MODULE_DIR,
"finmag%s_exch_density.npy" % demagsolver),
np.array(finmag_exch))
np.save(
os.path.join(MODULE_DIR,
"finmag%s_demag_density.npy" % demagsolver),
np.array(finmag_demag))
fh.close()
fe.close()
def compute_field(n=1, m0=(1, 0, 0), pbc=None):
assert n >= 1 and n % 2 == 1
Ms = 1e6
sim = Simulation(mesh, Ms, unit_length=1e-9, name='dy', pbc=pbc)
sim.set_m(m0)
parameters = {
'absolute_tolerance': 1e-10,
'relative_tolerance': 1e-10,
'maximum_iterations': int(1e5)
}
Ts = []
for i in range(-n / 2 + 1, n / 2 + 1):
Ts.append((10. * i, 0, 0))
demag = Demag(Ts=Ts)
demag.parameters['phi_1'] = parameters
demag.parameters['phi_2'] = parameters
sim.add(demag)
sim.set_m((1, 0, 0))
field1 = sim.llg.effective_field.get_dolfin_function('Demag')
sim.set_m((0, 0, 1))
field2 = sim.llg.effective_field.get_dolfin_function('Demag')
return (field1(0, 0, 0) / Ms, field2(0, 0, 0) / Ms)
def compute_scalar_potential_llg(mesh, m_expr=df.Constant([1, 0, 0]), Ms=1.):
S3 = df.VectorFunctionSpace(mesh, "Lagrange", 1, dim=3)
m = Field(S3, value=m_expr)
m.set_with_numpy_array_debug(helpers.fnormalise(m.get_numpy_array_debug()))
demag = Demag()
demag.setup(m, Field(df.FunctionSpace(mesh, 'DG', 0), Ms), unit_length=1)
phi = demag.compute_potential()
normalise_phi(phi, mesh)
return phi
def compute_scalar_potential_native_gcr(mesh,
m_expr=df.Constant([1, 0, 0]),
Ms=1.0):
gcrdemag = Demag("GCR")
V = df.VectorFunctionSpace(mesh, "Lagrange", 1)
m = Field(V, value=m_expr)
m.set_with_numpy_array_debug(helpers.fnormalise(m.get_numpy_array_debug()))
gcrdemag.setup(m, Ms, unit_length=1)
phi1 = gcrdemag.compute_potential()
normalise_phi(phi1, mesh)
return phi1
def demag_energy():
mesh = from_geofile(os.path.join(MODULE_DIR, "sphere_fine.geo"))
S3 = df.VectorFunctionSpace(mesh, "Lagrange", 1)
m_function = df.interpolate(df.Constant((1, 0, 0)), S3)
m = Field(S3, m_function)
demag = Demag('FK')
demag.setup(m, Field(df.FunctionSpace(mesh, 'DG', 0), Ms), unit_length=1)
E = demag.compute_energy()
rel_error = abs(E - E_analytical) / abs(E_analytical)
print "Energy with FK method: {}.".format(E)
return E, rel_error
def __init__(self, mesh):
self.mesh = mesh
self.S1 = df.FunctionSpace(mesh, 'CG', 1)
self.S3 = df.VectorFunctionSpace(mesh, 'CG', 1, dim=3)
#zero = df.Expression('0.3')
m_init = df.Constant([1, 1, 1.0])
self.m = df.interpolate(m_init, self.S3)
self.field = df.interpolate(m_init, self.S3)
self.dmdt = df.interpolate(m_init, self.S3)
self.spin = self.m.vector().array()
self.t = 0
#It seems it's not safe to specify rank in df.interpolate???
self._alpha = df.interpolate(df.Constant("0.001"), self.S1)
self._alpha.vector().set_local(self._alpha.vector().array())
print 'dolfin', self._alpha.vector().array()
self.llg = LLG(self.S1, self.S3, unit_length=1e-9)
#normalise doesn't work due to the wrong order
self.llg.set_m(m_init, normalise=True)
parameters = {
'absolute_tolerance': 1e-10,
'relative_tolerance': 1e-10,
'maximum_iterations': int(1e5)
}
demag = Demag()
demag.parameters['phi_1'] = parameters
demag.parameters['phi_2'] = parameters
self.exchange = Exchange(13e-12)
self.zeeman = Zeeman([0, 0, 1e5])
self.llg.effective_field.add(self.exchange)
#self.llg.effective_field.add(demag)
self.llg.effective_field.add(self.zeeman)
self.m_petsc = df.as_backend_type(self.llg.m_field.f.vector()).vec()
self.h_petsc = df.as_backend_type(self.field.vector()).vec()
self.alpha_petsc = df.as_backend_type(self._alpha.vector()).vec()
self.dmdt_petsc = df.as_backend_type(self.dmdt.vector()).vec()
alpha = 0.001
gamma = 2.21e5
LLG1 = -gamma / (1 + alpha * alpha) * df.cross(
self.m,
self.field) - alpha * gamma / (1 + alpha * alpha) * df.cross(
self.m, df.cross(self.m, self.field))
self.L = df.dot(LLG1, df.TestFunction(self.S3)) * df.dP
def setup_finmag():
mesh = from_geofile(os.path.join(MODULE_DIR, "sphere.geo"))
S3 = df.VectorFunctionSpace(mesh, "Lagrange", 1)
m = Field(S3)
m.set(df.Constant((1, 0, 0)))
Ms = 1
demag = Demag()
demag.setup(m,
Field(df.FunctionSpace(mesh, 'DG', 0), Ms),
unit_length=1e-9)
H = demag.compute_field()
return dict(m=m, H=H, Ms=Ms, S3=S3, table=start_table())
def run_finmag():
"""Run the finmag simulation and store data in averages.txt."""
sim = Sim(mesh, Ms, unit_length=unit_length)
sim.alpha = 0.5
sim.set_m((1, 0, 1))
exchange = Exchange(13.0e-12)
sim.add(exchange)
demag = Demag(solver="FK")
sim.add(demag)
fh = open(os.path.join(MODULE_DIR, "averages.txt"), "w")
fe = open(os.path.join(MODULE_DIR, "energies.txt"), "w")
logger.info("Time integration")
times = np.linspace(0, 3.0e-10, 61)
for counter, t in enumerate(times):
# Integrate
sim.run_until(t)
# Save averages to file
mx, my, mz = sim.m_average
fh.write(str(t) + " " + str(mx) + " " + str(my) + " " + str(mz) + "\n")
# Energies
E_e = exchange.compute_energy()
E_d = demag.compute_energy()
fe.write(str(E_e) + " " + str(E_d) + "\n")
# Energy densities
if counter == 10:
exch_energy = exchange.energy_density_function()
demag_energy = demag.energy_density_function()
finmag_exch, finmag_demag = [], []
R = range(100)
for i in R:
finmag_exch.append(exch_energy([15, 15, i]))
finmag_demag.append(demag_energy([15, 15, i]))
# Store data
np.save(os.path.join(MODULE_DIR, "finmag_exch_density.npy"),
np.array(finmag_exch))
np.save(os.path.join(MODULE_DIR, "finmag_demag_density.npy"),
np.array(finmag_demag))
fh.close()
fe.close()
def example3(Ms):
x0 = y0 = z0 = 0
x1 = 500
y1 = 10
z1 = 500
nx = 50
ny = 1
nz = 1
mesh = df.Box(x0, y0, z0, x1, y1, z1, nx, ny, nz)
sim = Sim(mesh, Ms, unit_length=1e-9)
sim.alpha = 0.01
sim.set_m((1, 0, 0.1))
H_app = Zeeman((0, 0, 5e5))
sim.add(H_app)
exch = fe.Exchange(13.0e-12)
sim.add(exch)
demag = Demag(solver="FK")
sim.add(demag)
llg = sim.llg
max_time = 1 * np.pi / (llg.gamma * 1e5)
ts = np.linspace(0, max_time, num=100)
for t in ts:
print t
sim.run_until(t)
df.plot(llg._m)
df.interactive()
def test_current_time():
size = 20e-9
simplices = 4
mesh = df.BoxMesh(df.Point(0, 0, 0), df.Point(size, size, size), simplices,
simplices, simplices)
Ms = 860e3
A = 13.0e-12
sim = Sim(mesh, Ms)
sim.set_m((1, 0, 0))
sim.add(Exchange(A))
sim.add(Demag())
t = 0.0
t_max = 1e-10
dt = 1e-12
while t <= t_max:
t += dt
sim.run_until(t)
# cur_t is equal to whatever time the integrator decided to probe last
assert not sim.integrator.cur_t == 0.0
# t is equal to our current simulation time
assert abs(sim.t - t) < epsilon
def test_differentiate_heff():
ns = [2, 2, 2]
mesh = df.BoxMesh(0, 0, 0, 1, 1, 1, *ns)
sim = Simulation(mesh, 1.2)
sim.set_m([1, 0, 0])
sim.add(Demag())
sim.add(Exchange(2.3 * mu0))
compute_H = compute_H_func(sim)
# Check that H_eff is linear without Zeeman
np.random.seed(1)
m1 = fnormalise(np.random.randn(*sim.m.shape))
m2 = fnormalise(np.random.randn(*sim.m.shape))
# TODO: need to use a non-iterative solver here to increase accuracy
assert np.max(
np.abs(compute_H(m1) + compute_H(m2) - compute_H(m1 + m2))) < 1e-6
# Add the zeeman field now
sim.add(Zeeman([2.5, 3.5, 4.3]))
# Check that both fd2 and fd4 give the same result
assert np.max(
np.abs(
differentiate_fd4(compute_H, m1, m2) -
differentiate_fd2(compute_H, m1, m2))) < 1e-10
def example2(Ms):
x0 = y0 = z0 = 0
x1 = 500
y1 = 10
z1 = 100
nx = 50
ny = 1
nz = 1
mesh = df.Box(x0, y0, z0, x1, y1, z1, nx, ny, nz)
S1 = df.FunctionSpace(mesh, "Lagrange", 1)
S3 = df.VectorFunctionSpace(mesh, "Lagrange", 1, dim=3)
llb = LLB(S1, S3)
llb.alpha = 0.01
llb.beta = 0.0
llb.M0 = Ms
llb.set_M((Ms, 0, 0))
llb.set_up_solver(jacobian=False)
llb.chi = 1e-4
H_app = Zeeman((0, 0, 5e5))
H_app.setup(S3, llb._M, Ms=1)
llb.interactions.append(H_app)
exchange = Exchange(13.0e-12, 1e-2)
exchange.chi = 1e-4
exchange.setup(S3, llb._M, Ms, unit_length=1e-9)
llb.interactions.append(exchange)
demag = Demag("FK")
demag.setup(S3, llb._M, Ms=1)
llb.interactions.append(demag)
max_time = 1 * np.pi / (llb.gamma * 1e5)
ts = np.linspace(0, max_time, num=100)
for t in ts:
print t
llb.run_until(t)
df.plot(llb._M)
df.interactive()
def create_initial_state():
print "Creating initial relaxed state."
sim = Sim(mesh, Ms=Ms, unit_length=1e-9)
sim.set_m(m_gen)
sim.alpha = 0.5
sim.add(Exchange(1.3e-11))
sim.add(Demag())
sim.relax()
np.savetxt(initial_m_file, sim.m)
def test_field():
"""
Test the demag field.
H_demag should be equal to -1/3 M, and with m = (1, 0 ,0)
and Ms = 1,this should give H_demag = (-1/3, 0, 0).
"""
# Using mesh with radius 10 nm (nmag ex. 1)
mesh = from_geofile(os.path.join(MODULE_DIR, "sphere1.geo"))
S3 = df.VectorFunctionSpace(mesh, "Lagrange", 1)
m_function = df.interpolate(df.Constant((1, 0, 0)), S3)
m = Field(S3, m_function)
demag = Demag()
demag.setup(m,
Field(df.FunctionSpace(mesh, 'DG', 0), Ms),
unit_length=1e-9)
# Compute demag field
H_demag = demag.compute_field()
H_demag.shape = (3, -1)
x, y, z = H_demag[0], H_demag[1], H_demag[2]
print "Max values in direction:"
print "x: %g, y: %g, z: %g" % (max(x), max(y), max(z))
print "Min values in direction:"
print "x: %g, y: %g, z: %g" % (min(x), min(y), min(z))
x, y, z = average(x), average(y), average(z)
print "Average values in direction"
print "x: %g, y: %g, z: %g" % (x, y, z)
# Compute relative erros
x = abs((x + 1. / 3 * Ms) / Ms)
y = abs(y / Ms)
z = abs(z / Ms)
print "Relative error:"
print "x: %g, y: %g, z: %g" % (x, y, z)
assert x < TOL, "x-average is %g, should be -1/3." % x
assert y < TOL, "y-average is %g, should be zero." % y
assert z < TOL, "z-average is %g, should be zero." % z
def example_simulation():
Ms = 8.6e5
mesh = df.BoxMesh(df.Point(0, 0, 0), df.Point(40, 20, 20), 10, 5, 5)
example = Simulation(mesh, Ms, name="sim_with_scheduling")
example.set_m((0.1, 1, 0))
example.add(Exchange(13.0e-12))
example.add(Demag())
example.add(Zeeman((Ms/2, 0, 0)))
return example
def run_simulation(stop_when_mx_eq_zero):
"""
Runs the simulation using field #1 from the problem description.
Stores the average magnetisation components regularly, as well as the
magnetisation when the x-component of the average magnetisation crosses
the value 0 for the first time.
"""
mesh = from_geofile(os.path.join(MODULE_DIR, "bar.geo"))
sim = Simulation(mesh, Ms, name="dynamics", unit_length=1e-9)
sim.alpha = alpha
sim.gamma = gamma
sim.set_m(np.load(m_0_file))
sim.add(Demag())
sim.add(Exchange(A))
"""
Conversion between mu0 * H in mT and H in A/m.
mu0 * H = 1 mT
= 1 * 1e-3 T
= 1 * 1e-3 Vs/m^2
divide by mu0 with mu0 = 4pi * 1e-7 Vs/Am
gives H = 1 / 4pi * 1e4 A/m
with the unit A/m which is indeed what we want.
Consequence:
Just divide the value of mu0 * H in Tesla
by mu0 to get the value of H in A/m.
"""
Hx = -24.6e-3 / mu0
Hy = 4.3e-3 / mu0
Hz = 0
sim.add(Zeeman((Hx, Hy, Hz)))
def check_if_crossed(sim):
mx, _, _ = sim.m_average
if mx <= 0:
print "The x-component of the spatially averaged magnetisation first crossed zero at t = {}.".format(
sim.t)
np.save(m_at_crossing_file, sim.m)
# When this function returns True, it means this event is done
# and doesn't need to be triggered anymore.
# When we return False, it means we want to stop the simulation.
return not stop_when_mx_eq_zero
sim.schedule(check_if_crossed, every=1e-12)
sim.schedule('save_averages', every=10e-12, at_end=True)
sim.schedule('save_vtk', every=10e-12, at_end=True, overwrite=True)
sim.run_until(2.0e-9)
return sim.t
def run_finmag():
# Setup
setupstart = time.time()
mesh = df.Box(0, 0, 0, 30, 30, 100, 15, 15, 50)
sim = Simulation(mesh, Ms=0.86e6, unit_length=1e-9)
sim.set_m((1, 0, 1))
demag = Demag("FK")
demag.parameters["poisson_solver"]["method"] = "cg"
demag.parameters["poisson_solver"]["preconditioner"] = "jacobi"
demag.parameters["laplace_solver"]["method"] = "cg"
demag.parameters["laplace_solver"]["preconditioner"] = "bjacobi"
sim.add(demag)
sim.add(Exchange(13.0e-12))
# Dynamics
dynamicsstart = time.time()
sim.run_until(3.0e-10)
endtime = time.time()
# Write output to results.txt
output = open(os.path.join(MODULE_DIR, "results.txt"), "a")
output.write("\nBackend %s:\n" % df.parameters["linear_algebra_backend"])
output.write("\nSetup: %.3f sec.\n" % (dynamicsstart - setupstart))
output.write("Dynamics: %.3f sec.\n\n" % (endtime - dynamicsstart))
output.write(str(default_timer))
output.close()
def run_simulation():
print "Running simulation of STT dynamics."
sim = Sim(mesh, Ms=Ms, unit_length=1e-9)
sim.set_m(np.loadtxt(initial_m_file))
sim.alpha = 0.01
sim.add(Exchange(1.3e-11))
sim.add(Demag())
sim.llg.use_slonczewski(J=0.1e12, P=0.4, d=10e-9, p=(0, 1, 0))
with open(averages_file, "w") as f:
dt = 5e-12
t_max = 10e-9
for t in np.arange(0, t_max, dt):
sim.run_until(t)
f.write("{} {} {} {}\n".format(t, *sim.m_average))
def relax_system(mesh):
sim = Sim(mesh, Ms=8.0e5, unit_length=1e-9)
sim.gamma = 2.211e5
sim.alpha = 1
sim.add(Exchange(A=13e-12))
sim.add(Demag())
sim.set_m(init_m)
sim.relax(stopping_dmdt=0.01)
np.save('m0.npy', sim.m)
df.plot(sim._m)
def run_simulation(lfactor, m_init, m_init_name=""):
L = lfactor * lexch
divisions = int(round(lfactor * 2)) # that magic number influences L
mesh = df.BoxMesh(df.Point(0, 0, 0), df.Point(L, L, L), divisions,
divisions, divisions)
exchange = Exchange(A)
anisotropy = UniaxialAnisotropy(K1, [0, 0, 1])
demag = Demag()
sim = Simulation(mesh, Ms)
sim.set_m(m_init)
sim.add(exchange)
sim.add(anisotropy)
sim.add(demag)
sim.relax()
# Save average magnetisation.
mx, my, mz = sim.m_average
with open(os.path.join(MODULE_DIR, "data_m.txt"), "a") as f:
t = time.asctime()
f.write("{} {} {} {} {} {}\n".format(m_init_name, lfactor, mx, my, mz,
t))
# Save energies.
# We could call sim.total_energy, but we want the individual contributions.
e_exc = exchange.compute_energy() / (sim.Volume * Km)
e_anis = anisotropy.compute_energy() / (sim.Volume * Km)
e_demag = demag.compute_energy() / (sim.Volume * Km)
e_total = e_exc + e_anis + e_demag # relative total energy density
with open(os.path.join(MODULE_DIR, "data_energies.txt"), "a") as f:
t = time.asctime()
f.write("{} {} {} {} {} {} {}\n".format(m_init_name, lfactor, e_total,
e_exc, e_anis, e_demag, t))
return e_total
def test_demag_energy_density():
"""
With a sphere mesh, unit magnetisation in x-direction,
we expect the demag energy to be
E = 1/6 * mu0 * Ms^2 * V.
(See section about demag solvers in the documentation
for how this is found.)
To make it simple, we define Ms = sqrt(6/mu0).
Energy density is then
E/V = 1.
"""
TOL = 5e-2
mesh = sphere(r=1.0, maxh=0.2)
S3 = df.VectorFunctionSpace(mesh, "Lagrange", 1)
mu0 = 4 * np.pi * 1e-7
demag = Demag()
m = Field(S3, value=(1, 0, 0))
Ms = np.sqrt(6.0 / mu0)
demag.setup(m, Field(df.FunctionSpace(mesh, 'DG', 0), Ms), 1)
density = demag.energy_density()
deviation = np.abs(density - 1.0)
print "Demag energy density (expect array of 1s):"
print density
print "Max deviation:", np.max(deviation)
assert np.max(deviation) < TOL, \
"Max deviation is %g, should be zero." % np.max(deviation)
def test_llb_save_data():
mesh = df.BoxMesh(df.Point(0, 0, 0), df.Point(10, 10, 5), 2, 2, 1)
def region1(coords):
if coords[2] < 0.5:
return True
else:
return False
def region2(coords):
return not region1(coords)
def init_Ms(coords):
if region1(coords) > 0:
return 8.6e5
else:
return 8.0e5
def init_T(pos):
return 1 * pos[2]
mat = Material(mesh, name='FePt', unit_length=1e-9)
mat.Ms = init_Ms
mat.set_m((1, 0, 0))
mat.T = init_T
mat.alpha = 0.1
assert(mat.T[0] == 0)
sim = LLB(mat, name='test_llb')
sim.set_up_solver()
ts = np.linspace(0, 1e-11, 11)
H0 = 1e6
sim.add(Zeeman((0, 0, H0)))
sim.add(Exchange(mat))
demag = Demag(solver='FK')
sim.add(demag)
sim.save_m_in_region(region1, name='bottom')
sim.save_m_in_region(region2, name='top')
sim.schedule('save_ndt', every=1e-12)
for t in ts:
print 't===', t
sim.run_until(t)
def setup_sim(self, m0):
Hz = [8e4, 0, 0] # A/m
A = 1.3e-11 # J/m
Ms = 800e3 # A/m
alpha = 1.
mesh = df.BoxMesh(0, 0, 0, *(self.box_size + self.box_divisions))
sim = Simulation(mesh, Ms)
sim.alpha = alpha
sim.set_m(m0)
sim.add(Demag())
sim.add(Exchange(A))
sim.add(Zeeman(Hz))
return sim
def test_compute_main():
Ms = 1700e3
A = 2.5e-6 * 1e-5
Hz = [10e3 * Oersted_to_SI(1.), 0, 0]
mesh = df.BoxMesh(0, 0, 0, 50, 50, 10, 6, 6, 2)
mesh = df.BoxMesh(0, 0, 0, 5, 5, 5, 1, 1, 1)
print mesh
# Find the ground state
sim = Simulation(mesh, Ms)
sim.set_m([1, 0, 0])
sim.add(Demag())
sim.add(Exchange(A))
sim.add(Zeeman(Hz))
sim.relax()
def test_compute_A():
Ms = 1700e3
A = 2.5e-6 * 1e-5
Hz = [10e3 * Oersted_to_SI(1.), 0, 0]
mesh = df.BoxMesh(0, 0, 0, 5, 5, 5, 2, 2, 2)
sim = Simulation(mesh, Ms)
sim.set_m([1, 0, 0])
sim.add(Demag())
# sim.add(Exchange(A))
# sim.add(Zeeman(Hz))
sim.relax()
print mesh
A0, m0 = compute_A(sim)
print A0[:3, :3]
print m0
def run_simulation(do_precession):
Ms = 0.86e6
mesh = df.BoxMesh(df.Point(0, 0, 0), df.Point(30e-9, 30e-9, 100e-9), 6, 6,
20)
sim = Simulation(mesh, Ms)
sim.set_m((1, 0, 1))
sim.do_precession = do_precession
sim.add(Demag())
sim.add(Exchange(13.0e-12))
averages = []
for t in ts:
sim.run_until(t)
averages.append(sim.m_average)
return np.array(averages)