def main():
from joommf.sim import Sim
from joommf.mesh import Mesh
from joommf.energies.exchange import Exchange
from joommf.energies.demag import Demag
from joommf.energies.zeeman import FixedZeeman
from joommf.drivers import evolver
# Mesh specification.
lx = ly = lz = 50e-9 # x, y, and z dimensions (m)
dx = dy = dz = 5e-9 # x, y, and z cell dimensions (m)
Ms = 8e5 # saturation magnetisation (A/m)
A = 1e-11 # exchange energy constant (J/m)
H = (1e3, 0, 0) # external magnetic field (A/m)
m_init = (0, 0, 1) # initial magnetisation
t_sim = 3e-9 # simulation time (s)
gamma = 2.21e5
alpha = 0.1
# Create a mesh.
mesh = Mesh((lx, ly, lz), (dx, dy, dz))
# Create a simulation object.
sim = Sim(mesh, Ms, name='dynamics_example', debug=True)
# Add energies.
sim.add_energy(Exchange(A))
sim.add_energy(Demag())
sim.add_energy(FixedZeeman(H))
sim.set_evolver(
evolver.LLG(t_sim, m_init, Ms, alpha, gamma, name='./Testing'))
# Set initial magnetisation.
sim.add_output('Magnetization', 100)
# Run simulation.
sim.run()
def test_llg_formatting():
t = 1.5e-9
m_init = (0, 1, 0)
Ms = 1e6
alpha = 0.01
gamma = 2.21e5
name = 'test_llg'
evolver_object = evolver.LLG(t, m_init, Ms, alpha, gamma, name)
mif_string = evolver_object.get_mif()
assert mif_string[0] == 'S'
assert mif_string[-1] == '\n'
assert mif_string[-2] == '\n'
def test_llg_mif():
t = 1.5e-9
m_init = (0, 1, 0)
Ms = 1e6
alpha = 0.01
gamma = 2.21e5
name = 'llgtest'
llg = evolver.LLG(t, m_init, Ms, alpha, gamma, name)
mif_string = llg.get_mif()
lines = mif_string.split('\n')
assert 'Specify Oxs_RungeKuttaEvolve' in lines[0]
assert 'alpha 0.01000' in lines[1]
assert 'gamma_G 221000.00000' in lines[2]
assert 'start_dm 0.01' in lines[3]
def test_min_dyn():
import glob
from joommf.sim import Sim
from joommf.mesh import Mesh
from joommf.energies.exchange import Exchange
from joommf.energies.demag import Demag
from joommf.drivers import evolver
from joommf.energies.zeeman import FixedZeeman
# Mesh specification.
lx = ly = lz = 50e-9 # x, y, and z dimensions (m)
dx = dy = dz = 5e-9 # x, y, and z cell dimensions (m)
Ms = 8e5 # saturation magnetisation (A/m)
A = 1e-11 # exchange energy constant (J/m)
H = (1e3, 0, 0) # external magnetic field (A/m)
m_init = (1, 0, 1)
gamma = 2.21e5
alpha = 0.1
# Create a mesh.
mesh = Mesh((lx, ly, lz), (dx, dy, dz))
# Create first simulation object.
sim1 = Sim(mesh, Ms, name='multiple_example_part1', debug=True)
t_sim = 1e-9
sim1.add_energy(Exchange(A))
sim1.add_energy(Demag())
sim1.add_energy(FixedZeeman(H))
sim1.set_evolver(
evolver.Minimiser(m_init, Ms, gamma))
# Set initial magnetisation.
# Run simulation.
sim1.add_output('Magnetization')
sim1.minimise()
m_init2 = glob.glob(sim1.mif_filename[:-4] + "*.omf")[-1]
sim2 = Sim(mesh, Ms, name='multiple_example_part2', debug=True)
sim2.add_energy(Exchange(A))
sim2.add_energy(Demag())
sim2.add_energy(FixedZeeman(H))
sim2.set_evolver(
evolver.LLG(t_sim, m_init2, Ms, alpha, gamma, name='evolver'))
# Set initial magnetisation.
# Run simulation.
sim2.run()