def get_bar(param):
g = geometry.square_ribbon(4) # create geometry of the system
#g = geometry.honeycomb_zigzag_ribbon(1) # create geometry of the system
g = geometry.chain() # create geometry of the system
g.r = np.array([g.r[0]])
g.a1 /= 2
g.r2xyz()
# g = g.supercell(4)
h = g.get_hamiltonian() # create hamiltonian
# h.get_bands()
# exit()
hr = h.copy()
hl = h.copy()
hc = h.copy()
# fermi and pairing
hr.shift_fermi(1.)
hl.shift_fermi(1.)
hc.shift_fermi(1.)
hr.add_swave(param)
hc.add_swave(0.0)
hl.add_swave(0.0)
# of the scattering centrl part
# create a junction object
ht = heterostructures.create_leads_and_central(hr,hl,hc,block_diagonal=False,
num_central = 1)
# hlist = [hc for i in range(80)] # create a list with the hamiltonians
hlist = [hc] # create a list with the hamiltonians
# ht = heterostructures.create_leads_and_central_list(hr,hl,hlist)
# ht.left_coupling *= .2
ht.right_coupling *= .1
return ht
def get_bar(delta1=0.0, delta2=0.0, phi=0.0, j=0.0, cou=1.0):
g = geometry.square_ribbon(4) # create geometry of the system
#g = geometry.honeycomb_zigzag_ribbon(1) # create geometry of the system
g = geometry.chain() # create geometry of the system
g.r = np.array([g.r[0]])
g.a1 /= 2
g.r2xyz()
# g = g.supercell(4)
h = g.get_hamiltonian() # create hamiltonian
h.shift_fermi(1.0)
# h.get_bands()
# exit()
hr = h.copy()
hl = h.copy()
hc = h.copy()
hc.add_zeeman([0., 0., j])
# hc.add_rashba(0.2)
# fermi and pairing
# hr.shift_fermi(1.)
# hl.shift_fermi(1.)
# hc.shift_fermi(1.)
hr.add_swave(delta=delta2)
hc.add_swave(delta=0.0)
hl.add_swave(delta=delta1, phi=phi)
# of the scattering centrl part
# create a junction object
ht = heterostructures.create_leads_and_central(hr,
hl,
hc,
block_diagonal=False,
num_central=1)
# hlist = [hc for i in range(80)] # create a list with the hamiltonians
hlist = [hc] # create a list with the hamiltonians
# ht = heterostructures.create_leads_and_central_list(hr,hl,hlist)
# ht.left_coupling *= .2
ht.right_coupling *= cou
return ht
# zigzag ribbon
import sys
sys.path.append("../../../pygra") # add pygra library
import geometry
import topology
import numpy as np
import phasediagram
g = geometry.chain() # 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(0.5) # add Rashba SOC
h.add_zeeman(x1+0.5) # add Zeeman field
h.shift_fermi(2.0) # add Zeeman field
h.add_swave(x2) # add swave pairing
phi = topology.berry_phase(h) # get the berry phase
return np.abs(phi/np.pi)
# now write the Phase diagram in a file
phasediagram.diagram2d(getz2,x=np.linspace(-1,1,20,endpoint=True),y=np.linspace(-1,2.,20,endpoint=True),nite=4)
import sys
sys.path.append("../../pygra") # add pygra library
import geometry # library to create crystal geometries
import hamiltonians # library to work with hamiltonians
import sculpt # to modify the geometry
import correlator
import numpy as np
import matplotlib.pyplot as plt
import kpm
g = geometry.chain()
g = g.supercell(100)
g.dimensionality = 0
h = g.get_hamiltonian()
h.shift_fermi(.4)
h.add_zeeman([.8, .8, .8])
h.add_rashba(.8)
i = 0
j = 7
(x, y, yi) = kpm.correlator0d(h.intra, npol=300, i=i, j=j)
(x2, y2, yi2) = correlator.correlator0d(h.intra, i=i, j=j, delta=0.1)
#print(np.trapz(y,x=x,dx=x[1]-x[0]))
plt.subplot(1, 2, 1)
plt.plot(x, y, marker="o", label="KPM")
plt.plot(x2, y2, marker="o", label="Green")
# zigzag ribbon
import sys
sys.path.append("../../../pygra") # add pygra library
import geometry
import scftypes
import numpy as np
# this spin calculates the spin stiffness of an interacting 1d chain
g = geometry.chain() # chain geometry
h0 = g.get_hamiltonian() # create hamiltonian of the system
fo = open("STIFFNESS.OUT","w") # open file
for a in np.linspace(0.,.2,20): # loop over angles, in units of pi
h = h0.copy()
h.generate_spin_spiral(angle=a,vector=[0.,1.,0.])
scf = scftypes.hubbardscf(h,filling=0.1,nkp=1000,U=2.5,silent=True,
mag=[[0.,0.,.1]],mix=0.01,maxerror=1e-4)
fo.write(str(a)+" "+str(scf.energy)+"\n") # write
print(a,scf.energy)
fo.close()
else: # RPA calculation
return rpachi(ms,U=U)
if __name__=="__main__":
import geometry
import hamiltonians
g = geometry.chain()
h = g.get_hamiltonian()
# h.add_antiferromagnetism(.1)
h.add_antiferromagnetism(.1)
energies = np.linspace(-1.,1.,100)
ms = chi1d(h,energies=energies)
ms = sumchi(ms) # sum all the elements
import pylab as py
# b = h.plot_bands()
py.plot(energies,ms.imag)
py.plot(energies,ms.real)
py.show()
import sys
sys.path.append("../../../pygra") # add pygra library
import geometry
import numpy as np
g = geometry.chain(400) # chain
g.dimensionality = 0
betas = np.linspace(0.0,4.0,30)
# loop over v's
def discard(w):
w2 = np.abs(w)*np.abs(w) # absolute value
n = len(w)
if np.sum(w2[0:n//10])>0.5 or np.sum(w2[9*n//10:n])>0.5: return False
else: return True
fo = open("LAMBDA_VS_V.OUT","w")
for beta in betas:
h = g.get_hamiltonian(has_spin=False)
import potentials
fun = potentials.aahf1d(v=2.5,beta=beta)
h.shift_fermi(fun)
(es,ls) = h.get_tails(discard=discard) # return the localization length
for (e,l) in zip(es,ls):
fo.write(str(beta)+" ")
fo.write(str(e)+" ")
fo.write(str(l)+"\n")
fo.flush()
import sys
sys.path.append("../../../pygra") # add pygra library
import geometry
import topology
g = geometry.chain(2) # create geometry of a zigzag ribbon
h = g.get_hamiltonian(has_spin=False) # get the Hamiltonian,spinless
delta = -0.1 # value of the perturbation
h.intra *= (1.+delta) # modify intra-hopping
h.inter *= (1.-delta) # modify inter-hopping
phi = topology.berry_phase(h) # get the berry phase
print(phi)
hf = h.supercell(100) # do a supercell
hf = hf.set_finite_system(periodic=False) # do an open finite system
hf.get_bands()
