# Add the root path of the pygra library
import os
import sys
sys.path.append(os.environ['PYGRAROOT'])
from pygra import geometry
from pygra import meanfield
import numpy as np
omega = 1. / np.sqrt(2)
g = geometry.bichain()
g = g.supercell(40) # get the geometry
g.dimensionality = 0
h = g.get_hamiltonian() # compute Hamiltonian
phi = 0.5
delta = 2. * np.cos(phi)
maf = 2. * np.sin(phi) * np.array([1., 0., 0.])
def fsc(r):
return delta * np.cos(omega * np.pi * 2 * r[0])
def faf(r):
return maf * np.sin(omega * np.pi * 2 * r[0])
h.add_antiferromagnetism(faf)
h.add_swave(fsc)
# Add the root path of the pygra library import os ; import sys ; sys.path.append(os.environ['PYGRAROOT']) from pygra import geometry from pygra import topology import numpy as np from pygra import phasediagram g = geometry.bichain() # create geometry of a chain def getz2(x1,x2): # calculate the Z2 invariant for certain Zeeman and Rashba h = g.get_hamiltonian(has_spin=True) # get the Hamiltonian, spinfull h.add_rashba(0.3) # add SOC h.shift_fermi(x2) # add SOC h.add_zeeman([0.,0.,0.3]) # add mass h.add_swave(x1) # add mass z2 = abs(topology.berry_phase(h,nk=40)/np.pi) # get the Z2 print(x1,x2,z2) return z2 # now write the Phase diagram in a file phasediagram.diagram2d(getz2,x=np.linspace(-.0,0.3,30,endpoint=True),y=np.linspace(0.,4.,30,endpoint=True),nite=1)
# Add the root path of the pygra library
import os ; import sys ; sys.path.append(os.environ['PYGRAROOT'])
from pygra import geometry
from pygra import hamiltonians
from pygra import sculpt # to modify the geometry
from pygra import correlator
from pygra import kpm
import numpy as np
import matplotlib.pyplot as plt
import time
g = geometry.bichain()
g = g.supercell(40)
g.center()
g.dimensionality = 0
g.write()
def fs(r):
if r[0]<0.0: return 0.5
else: return 0.0
def faf(r):
if r[0]>0.0: return 0.5
else: return 0.0
h = g.get_hamiltonian()
h.add_antiferromagnetism(faf)
h.add_swave(fs)
from pygra import ldos
#ldos.multi_ldos(h,np.linspace(-3.0,3.0,40),delta=0.1)
h.get_bands()
# Add the root path of the pygra library
import os ; import sys
sys.path.append(os.path.dirname(os.path.realpath(__file__))+"/../../../src")
from pygra import geometry
from pygra import potentials
import numpy as np
g = geometry.bichain(100) # bipartitie chain geometry
g.dimensionality = 0 # zero dimensional (finite system)
def get_energies(omega=0.0,phi=0.0):
"""Compute the energies"""
h = g.get_hamiltonian(has_spin=True) # generate Hamiltonian
def fm(r):
"""Function that add the antiferromagnetism"""
return .5 + .5*np.cos(2*np.pi*(omega*r[0]+phi)) # local AF magnetization
h.add_antiferromagnetism(fm)
inds,es = h.get_bands() # compute eigenstates
return es # return eigenstates
# compute the Hofstadter butterfly
f = open("HOFSTADTER.OUT","w") # output file
omegas = np.linspace(0.,1.,100) # different frequencies
for omega in omegas:
es = get_energies(omega=omega) # return energies
