Energy

Energy class is used to compute the classical ground state energy of the Hamiltonian. It is created based on some spin Hamiltonian

>>> import numpy as np
>>> import magnopy
>>> cell = np.eye(3)
>>> atoms = {
...     "names" : ["Fe1"],
...     "species" : ["Fe"],
...     "positions" : [[0.0, 0.0, 0.0]],
...     "spins" : [5/2],
...     "g_factors" : [2]
... }
>>> convention = magnopy.Convention(
...     multiple_counting=True, spin_normalized=False, c1=1, c21=1, c22=-1 / 2, c31=1, c41=1
... )
>>> spinham = magnopy.SpinHamiltonian(cell=cell, atoms=atoms, convention=convention)
>>> spinham.add_21(alpha=0, parameter=np.diag([2, -1, -1]))
>>> spinham.add_22(alpha = 0, beta = 0, nu = (1, 0, 0), parameter = np.eye(3))
>>> spinham.add_22(alpha = 0, beta = 0, nu = (0, 1, 0), parameter = np.eye(3))
>>> spinham.add_22(alpha = 0, beta = 0, nu = (0, 0, 1), parameter = np.eye(3))
>>> energy = magnopy.Energy(spinham=spinham)

And then takes a set of spin directions to compute \(E^{(0)}\) (Energy.E_0())

>>> energy.E_0(spin_directions = [[0, 0, 1]])
-25.0
>>> energy.E_0(spin_directions = [[0, 1, 0]])
-25.0
>>> energy.E_0(spin_directions = [[1, 0, 0]])
-6.25