def add_magnetism(h, m):
""" Adds magnetism to the intracell hopping"""
intra = h.intra # intracell hopping
if h.has_spin:
natoms = len(h.geometry.r) # number of atoms
# create the array
out = [[None for j in range(natoms)]
for i in range(natoms)] # output matrix
if checkclass.is_iterable(m):
print(natoms)
if checkclass.is_iterable(
m[0]) and len(m) == natoms: # input is an array
mass = m # use as arrays
elif len(m) == 3: # single exchange provided
mass = [m for i in range(natoms)] # use as arrays
else:
raise
elif callable(m): # input is a function
mass = [m(h.geometry.r[i])
for i in range(natoms)] # call the function
else:
print("Wrong input in add_magnetism")
raise
for i in range(natoms): # loop over atoms
mi = mass[i] # select the element
# add contribution to the Hamiltonian
out[i][i] = sx * mi[0] + sy * mi[1] + sz * mi[2]
out = bmat(out) # turn into a matrix
h.intra = h.intra + h.spinful2full(out) # Add matrix
else:
print("no AF for unpolarized hamiltonian")
raise
def add_antiferromagnetism(h, m, axis):
""" Adds to the intracell matrix an antiferromagnetic imbalance """
intra = h.intra # intracell hopping
if h.geometry.has_sublattice: pass # if has sublattice
else: # if does not have sublattice
print("WARNING, no sublattice present")
return 0. # if does not have sublattice
if h.has_spin:
natoms = len(h.geometry.x) # number of atoms
out = [[None for j in range(natoms)]
for i in range(natoms)] # output matrix
# create the array
if checkclass.is_iterable(m): # iterable, input is an array
mass = m # use the input array
elif callable(m): # input is a function
mass = [m(h.geometry.r[i])
for i in range(natoms)] # call the function
else: # assume it is a float
mass = [m for i in range(natoms)] # create list
for i in range(natoms): # loop over atoms
mi = mass[i] # select the element
if callable(axis):
ax = np.array(axis(h.geometry.r[i])) # call the function
else:
ax = np.array(axis) # convert to array
ax = ax / np.sqrt(ax.dot(ax)) # normalize the direction
# add contribution to the Hamiltonian
out[i][i] = mi * (sx * ax[0] + sy * ax[1] +
sz * ax[2]) * h.geometry.sublattice[i]
out = bmat(out) # turn into a matrix
h.intra = h.intra + h.spinful2full(out) # Add matrix
else:
print("no AF for unpolarized hamiltonian")
raise
def shift_fermi(h, fermi):
""" Moves the fermi energy of the system, the new value is at zero"""
r = h.geometry.r # positions
n = len(r) # number of sites
if checkclass.is_iterable(fermi): # iterable
if len(fermi) == n: # same number of sites
h.intra = h.intra + h.spinless2full(sparse_diag([fermi], [0]))
else:
raise
else:
rc = [i for i in range(n)] # index
datatmp = [] # data
for i in range(n): # loop over positions
if callable(fermi): fshift = fermi(r[i]) # fermi shift
else: fshift = fermi # assume it is a number
datatmp.append(fshift) # append value
m = csc_matrix((datatmp, (rc, rc)),
shape=(n, n)) # matrix with the shift
h.intra = h.intra + h.spinless2full(m) # Add matrix
return
def convert(z):
if checkclass.is_iterable(z): return z # iterable, input is an array
else: return [0., 0., z] # input is a number