def square_2d_hamiltonian(Jx=-5e-21,
Jy=-5e-21,
dmi=5e-21,
k1=np.array([-000 * mu_B]),
k1dir=np.array([[0.0, 0, 1.0]])):
atoms = Atoms(
symbols="H",
positions=[[0, 0, 0]],
cell=[[1, 0, 0], [0, 1, 0], [0, 0, 1]])
spin = np.array([[0, 1, 0]])
ham = SpinHamiltonian(
cell=atoms.cell,
pos=atoms.get_scaled_positions(),
spinat=spin,
zion=atoms.get_atomic_numbers())
ham.gilbert_damping = [1.0]
J = {
(0, 0, (1, 0, 0)): Jx,
(0, 0, (-1, 0, 0)): Jx,
(0, 0, (0, 1, 0)): Jy,
(0, 0, (0, -1, 0)): Jy,
}
ham.set_exchange_ijR(exchange_Jdict=J)
DMI = {
(0, 0, (1, 0, 0)): [0, -dmi, 0],
(0, 0, (-1, 0, 0)): [0,dmi, 0],
(0, 0, (0, 1, 0)): [dmi,0, 0 ],
(0, 0, (0, -1, 0)): [-dmi, 0, 0],
}
ham.set_dmi_ijR(dmi_ddict=DMI)
ham.set_uniaxial_mca(k1, k1dir)
return ham
def __init__(self, fname=None, sc_matrix=None, ham=None):
self.params = SpinParams()
if ham is not None:
self._ham=ham
elif fname is not None:
self.read_from_file(fname)
else:
self._ham = SpinHamiltonian()
if sc_matrix is not None:
self.make_supercell(sc_matrix)
self.mover = SpinMover(self._ham)
def traingular_2d_hamiltonian(J1=-0e-21,
k1=np.array([-000 * mu_B]),
k1dir=np.array([[0.0, 0, 1.0]])):
"""
Isolated spin in an applied field. field:10T, time step: 1fs.
Total time: 100 ps, No Langevin term.
"""
# make model
atoms = Atoms(
symbols="H",
positions=[[0, 0, 0]],
cell=[[1, 0, 0], [-1.0 / 2, np.sqrt(3) / 2, 0], [0, 0, 1]])
spin = np.array([[0, 1, 0]])
ham = SpinHamiltonian(
cell=atoms.cell,
pos=atoms.get_scaled_positions(),
spinat=spin,
zion=atoms.get_atomic_numbers())
ham.gilbert_damping = [1.0]
J = {
(0, 0, (1, 0, 0)): J1,
(0, 0, (0, 1, 0)): J1,
(0, 0, (1, 1, 0)): J1,
(0, 0, (-1, 0, 0)): J1,
(0, 0, (0, -1, 0)): J1,
(0, 0, (-1, -1, 0)): J1,
}
ham.set_exchange_ijR(exchange_Jdict=J)
ham.set_uniaxial_mca(k1, k1dir)
return ham
def exchange_1d_hamiltonian(J1=3e-21,
J2=0e-21,
DMI=[0, 0, 0e-21],
k1=np.array([-0 * mu_B]),
k1dir=np.array([[0.0, 0.0, 1.0]]),
plot_type='2d'):
# make model
atoms = Atoms(symbols="H", positions=[[0, 0, 0]], cell=[1, 1, 1])
spin = np.array([[0, 1, 0]])
ham = SpinHamiltonian(
cell=atoms.cell,
pos=atoms.get_scaled_positions(),
spinat=spin,
zion=atoms.get_atomic_numbers())
ham.gilbert_damping = [0.8]
#ham.gyro_ratio=[1.0]
J = {
(0, 0, (1, 0, 0)): J1,
(0, 0, (-1, 0, 0)): J1,
(0, 0, (2, 0, 0)): J2,
(0, 0, (-2, 0, 0)): J2,
}
ham.set_exchange_ijR(exchange_Jdict=J)
k1 = k1
k1dir = k1dir
ham.set_uniaxial_mca(k1, k1dir)
DMIval = np.array(DMI)
DMI = {
#(0, 0, (0, 0, 1)): DMIval,
#(0, 0, (0, 0, -1)): -DMIval,
#(0, 0, (0, 1, 0)): DMIval,
#(0, 0, (0, -1, 0)): -DMIval,
(0, 0, (-1, 0, 0)):
-DMIval,
(0, 0, (1, 0, 0)):
DMIval,
}
ham.set_dmi_ijR(dmi_ddict=DMI)
return ham
def cubic_3d_hamiltonian(Jx=-0e-21,
Jy=-0e-21,
Jz=0e-21,
DMI=[0, 0, 0e-21],
k1=np.array([-0 * mu_B]),
k1dir=np.array([[0.0, 0, 1.0]])):
atoms = Atoms(
symbols="H",
positions=[[0, 0, 0]],
cell=[[1, 0, 0], [0, 1, 0], [0, 0, 1]])
spin = np.array([[0, 1, 0]])
ham = SpinHamiltonian(
cell=atoms.cell,
pos=atoms.get_scaled_positions(),
spinat=spin,
zion=atoms.get_atomic_numbers())
ham.gilbert_damping = [1.0]
J = {
(0, 0, (1, 0, 0)): Jx,
(0, 0, (-1, 0, 0)): Jx,
(0, 0, (0, 1, 0)): Jy,
(0, 0, (0, -1, 0)): Jy,
(0, 0, (0, 0, 1)): Jz,
(0, 0, (0, 0, -1)): Jz,
}
ham.set_exchange_ijR(exchange_Jdict=J)
ham.set_uniaxial_mca(k1, k1dir)
DMIval = np.array(DMI)
DMI = {
(0, 0, (0, 0, 1)): DMIval,
(0, 0, (0, 0, -1)): -DMIval,
#(0, 0, (0, 1, 0)): DMIval,
#(0, 0, (0, -1, 0)): -DMIval,
#(0, 0, (-1, 0, 0)): -DMIval,
#(0, 0, (1, 0, 0)): DMIval,
}
ham.set_dmi_ijR(dmi_ddict=DMI)
return ham
class SpinModel():
def __init__(self, fname=None, sc_matrix=None, ham=None):
self.params = SpinParams()
if ham is not None:
self._ham=ham
elif fname is not None:
self.read_from_file(fname)
else:
self._ham = SpinHamiltonian()
if sc_matrix is not None:
self.make_supercell(sc_matrix)
self.mover = SpinMover(self._ham)
@property
def ham(self):
return self._ham
def add_term(self, term, name=None):
self._ham.add_Hamiltonian_term(term, name=name)
@ham.setter
def ham(self, ham):
self._ham = ham
@property
def S(self):
return self.mover.s
@property
def nspin(self):
return self._ham.nspin
def read_from_file(self, fname):
self._ham = read_spin_ham_from_file(fname)
def set(self, **kwargs):
self.params.set(**kwargs)
self.mover.set(
time_step=self.params.time_step,
temperature=self.params.temperature,
total_time=self.params.total_time,
)
def make_supercell(self, sc_matrix=None, supercell_maker=None):
self._ham = self._ham.make_supercell(
sc_matrix=sc_matrix, supercell_maker=supercell_maker)
self.mover = SpinMover(self._ham)
return self
def run_one_step(self):
self.mover.run_one_step()
def run_time(self):
self.mover.run()
def plot_magnon_band(
self,
kvectors=np.array([[0, 0, 0], [0.5, 0, 0], [0.5, 0.5, 0],
[0, 0, 0], [.5, .5, .5]]),
knames=['$\Gamma$', 'X', 'M', '$\Gamma$', 'R'],
supercell_matrix=None,
npoints=100,
color='red',
ax=None,
kpath_fname=None,
):
self._ham.plot_magnon_band(
kvectors=kvectors,
knames=knames,
supercell_matrix=supercell_matrix,
npoints=npoints,
color=color,
ax=ax,
kpath_fname=kpath_fname)