def test_get_energy(self):
m = IsingModel(5, 6)
from pymatgen.core.periodic_table import Specie
s = Structure.from_file(os.path.join(test_dir, "LiFePO4.cif"))
s.replace_species({"Fe": Specie("Fe", 2, {"spin": 4})})
self.assertAlmostEqual(m.get_energy(s), 172.81260515787977)
s[4] = Specie("Fe", 2, {"spin": -4})
s[5] = Specie("Fe", 2, {"spin": -4})
self.assertAlmostEqual(m.get_energy(s), 51.97424405382921)
def test_get_energy(self):
m = IsingModel(5, 6)
from pymatgen.core.periodic_table import Specie
s = Structure.from_file(os.path.join(test_dir, "LiFePO4.cif"))
s.replace_species({"Fe": Specie("Fe", 2, {"spin": 4})})
self.assertAlmostEqual(m.get_energy(s), 172.81260515787977)
s[4] = Specie("Fe", 2, {"spin": -4})
s[5] = Specie("Fe", 2, {"spin": -4})
self.assertAlmostEqual(m.get_energy(s), 51.97424405382921)
def objective_function_Ising(x, structures):
"""
:param x: list of E0 and J
:param structures: vasp calculated structures
:return: error = (property_predicted - property_target) ** 2 / delta_tolerance
"""
model = IsingModel(x[1], config['cutoff_radius'])
error = sum([(model.get_energy(st) + x[0] - st.vasp_energy)**2
for st in structures]) / config['delta_tolerance']
return error
idx = int(np.where(np.isclose(self.distances, dist))[0])
energy -= self.j[idx] * s1 * getattr(site.specie, "spin", 0)
return energy
#atoms = read_vasp('POSCAR2')
#write_vasp('POSCAR', sort(atoms), vasp5=True, direct=True, label=atoms.get_chemical_formula())
if __name__ == '__main__':
"""
J = [0.00240319, 0.00224361, 0.00146472, 0.00125072, 0.00122649]
model_uuu = MultiIsingModel(J, 5.0, Structure.from_file('2FEPOSCAR'), [3, 3])
model_uuu.recommended_j()
model_uud = MultiIsingModel(J, 5.0, Structure.from_file('2FEPOSCAR'), [3, -3])
uuu = model_uuu.get_energy()
uud = model_uud.get_energy()
print(uuu - uud)
"""
J = -0.03489
uu = Structure.from_file('2FEPOSCAR')
ud = uu.copy()
uu.add_spin_by_site([3.291, 3.291])
ud.add_spin_by_site([3.285, -3.285])
model = IsingModel(J, 5.0)
print(model.get_energy(uu) - model.get_energy(ud))
uuu = Structure.from_file('POSCAR3')
uud = uu.copy()
uuu.add_spin_by_site([3, 3, 3])
uud.add_spin_by_site([3, 3, -3])
model = IsingModel(J, 5.0)
print(model.get_energy(uuu) - model.get_energy(uud))
class MCModel:
def __init__(self, config):
self.config = config
self.mode = self.config['mode']
self.savefile = self.config['savefile']
if self.mode == 'calculate':
self.structure = self.make_simulation_grid(self.config['dim'])
self.temperature = self.config[
'temperature'] * 8.6173303e-05 # Boltzmann constant in eV/K
self.init_weight = np.array([
x for x in self.config['initial_spin_weight']
]) / sum(self.config['initial_spin_weight'])
self.spins = None
self.initialize_spins()
self.history = [self.structure.copy()]
self.size = len(self.structure)
self.model = IsingModel(j=self.config['J'],
max_radius=self.config['max_radius'])
self.step = 0
self.maxsteps = self.config['maxsteps']
self.energy = self.model.get_energy(self.structure)
self.get_magnetization()
self.start_time = None
self.saveevery = self.config['saveevery']
self.force_stop = False
elif self.mode == 'plot':
with open(self.savefile, 'rb') as f:
self.history = pickle.load(f)
def make_simulation_grid(self, dim):
atoms = bulk("Fe")
structure = AseAtomsAdaptor().get_structure(atoms)
structure.make_supercell(dim)
return structure
def initialize_spins(self):
self.spins = np.random.choice(
[self.config['spin'], -self.config['spin']],
len(self.structure),
p=self.init_weight)
self.structure.add_spin_by_site(self.spins)
def make_step(self):
self.step += 1
test_step = deepcopy(self.structure.copy())
idx = np.random.randint(self.size)
self.spins[idx] *= -1
test_step.add_spin_by_site(self.spins)
energy_after_step = self.model.get_energy(test_step)
change = energy_after_step - self.energy
p = np.random.rand()
print(np.exp((-1.0 * change) / self.temperature), p)
if change < 0:
self.structure = deepcopy(test_step.copy())
self.energy = energy_after_step
self.structure.add_spin_by_site(self.spins)
elif np.exp((-1.0 * change) / self.temperature) > p:
self.structure = deepcopy(test_step.copy())
self.energy = energy_after_step
self.structure.add_spin_by_site(self.spins)
else:
self.spins[idx] *= -1
self.history.append(self.structure.copy())
self.get_magnetization()
if self.step % self.saveevery == 0:
with open(self.savefile, 'wb') as f:
pickle.dump(self.history, f)
if os.path.exists('stop'):
self.force_stop = True
def get_magnetization(self):
m = sum([
getattr(self.structure[idx].specie, "spin")
for idx in range(self.size)
]) / self.size
print(
f'Step {self.step:05d}: magnetization {m:.8f} energy {self.energy:0.6f}'
)
def run(self):
self.start_time = time()
while self.step < self.maxsteps:
self.make_step()
if self.force_stop:
break
runtime = time() - self.start_time
print(
f'Run time {runtime:.1f} seconds, {runtime/self.maxsteps:.3f} second per step'
)
def plot(self):
pass