def func_to_parallelize(U):
"""Function to parallelize"""
# all the variables must be internal!
from pygra import geometry
from pygra import meanfield
g = geometry.honeycomb_lattice()
h = g.get_hamiltonian() # create hamiltonian of the system
mf = meanfield.guess(h,mode="antiferro") # antiferro initialization
# perform SCF with specialized routine for Hubbard
scf = meanfield.hubbardscf(h,nk=20,filling=0.5,U=U,verbose=1,
mix=0.9,mf=mf)
# alternatively use
h = scf.hamiltonian # get the Hamiltonian
gap = h.get_gap() # compute the gap
return gap
h0 = g.get_hamiltonian() # create hamiltonian of the system
ds = []
Us = np.linspace(0.0, 10.0, 10)
f = open("DELTA_VS_T_VS_MU.OUT", "w")
h0.add_swave(0.0)
for U in Us:
h = h0.copy()
os.system("rm -rf *.pkl")
#scf = scftypes.attractive_hubbard(h,nk=10,mix=0.9,mf=None,g=-2.0,T=t)
mf = 10 * (meanfield.guess(h, "swave") + meanfield.guess(h, "CDW"))
mf = meanfield.guess(h, "swave") #+ meanfield.guess(h,"CDW"))
mf = meanfield.guess(h, "random") #+ meanfield.guess(h,"CDW"))
scf = meanfield.hubbardscf(
h,
nk=10,
mix=0.5,
U=-U,
mf=mf,
filling=0.5,
verbose=1,
constrains=["no_charge"] # this forces the system to ignore CDW
)
hscf = scf.hamiltonian
# rho = hscf.get_filling()
d = np.abs(np.mean(hscf.extract("swave")))
f.write(str(U) + " ")
f.write(str(d) + "\n")
print("Doing", U)
f.flush()
f.close()
# Add the root path of the pygra library
import os
import sys
sys.path.append(os.path.dirname(os.path.realpath(__file__)) + "/../../../src")
# zigzag ribbon
import numpy as np
from pygra import geometry
from pygra import meanfield
g = geometry.honeycomb_lattice()
h = g.get_hamiltonian() # create hamiltonian of the system
h.add_swave(0.001) # add swave
mf = meanfield.guess(h, mode="swave", fun=0.02)
scf = meanfield.hubbardscf(h, nk=5, mf=mf, U=-2.0, filling=0.7)
h = scf.hamiltonian
print("Delta", h.extract("swave"))
print("Onsite", h.extract("density"))
h.write_swave()
h.get_bands()
#scf.hamiltonian.get_bands(operator="electron")
# Add the root path of the pygra library
import os
import sys
sys.path.append(os.environ['PYGRAROOT'])
# zigzag ribbon
import numpy as np
from pygra import geometry
from pygra import meanfield
g = geometry.honeycomb_lattice()
g.write()
Us = np.linspace(0., 4., 10) # different Us
f = open("EVOLUTION.OUT", "w") # file with the results
for U in Us: # loop over Us
h = g.get_hamiltonian() # create hamiltonian of the system
mf = meanfield.guess(h, mode="antiferro") # antiferro initialization
# perform SCF with specialized routine for Hubbard
scf = meanfield.hubbardscf(h, nk=20, filling=0.5, U=U, mix=0.9, mf=mf)
# alternatively use
# scf = scftypes.selfconsistency(h,nkp=20,filling=0.5,g=U,
# mix=0.9,mf=mf)
h = scf.hamiltonian # get the Hamiltonian
gap = h.get_gap() # compute the gap
f.write(str(U) + " " + str(gap) + "\n") # save in a file
f.close()
# if you wanted to modify the Hamiltonian, just put here your data
# h.geometry.r = rs # new positions
# h.geometry.r2xyz() # update
# h.geometry.a1 = a1 # first lattice vector
# h.geometry.a2 = a2 # second lattice vector
# h.intra = intra # your (spinless) intra cell hopping
# h.tx = tx # your (spinless) (1,0,0) hopping matrix
# h.ty = ty # your (spinless) (0,1,0) hopping matrix
# h.txy = txy # your (spinless) (1,1,0) hopping matrix
# h.txmy = txmy # your (spinless) (1,-1,0) hopping matrix
# now make the Hamiltonian spinful
h.turn_spinful()
# let us do now a mean field calculation
from pygra import meanfield
mf = meanfield.guess(h, "randomXY") # random initial guess in XY plane
# if you want to restart a calculation, just uncomment the mf=None line
# that will force the code to pick the latest mean field from a file
#mf = None
scf = meanfield.hubbardscf(h,
U=6.0,
mf=mf,
verbose=1,
filling=0.5,
nk=6,
mix=0.5) # perform SCF calculation
# this will write the magnetization to MAGNETISM.OUT
scf.hamiltonian.write_magnetization(nrep=2) # write magnetization in a file
# Add the root path of the pygra library
import os
import sys
sys.path.append(os.path.dirname(os.path.realpath(__file__)) + "/../../../src")
import numpy as np
from pygra import geometry
from pygra import meanfield
# this example performs a selconsistent calculation in a dimer
g = geometry.lieb_lattice() # generate the geometry
Us = np.linspace(0., 2., 20) # different Hubbard U
mz = [] # lists to store magnetizations
for U in Us: # loop over Hubbard U
h = g.get_hamiltonian() # create hamiltonian of the system
mf = meanfield.guess(h, mode="antiferro") # antiferro initialization
scf = meanfield.hubbardscf(h, filling=0.5, U=U, mf=mf, nk=5) # perform SCF
mz0 = scf.hamiltonian.compute_vev("sz", nk=5) # expectation value
mz.append(np.sum(np.abs(mz0))) # total magentization
# now plot all the results
import matplotlib.pyplot as plt
plt.plot(Us, mz, marker="o", c="red")
plt.xlabel("Hubbard U")
plt.ylabel("Magnetic moment")
plt.show()
# Add the root path of the pygra library
import os ; import sys ; sys.path.append(os.environ['PYGRAROOT'])
# zigzag ribbon
import numpy as np
from pygra import geometry
from pygra import scftypes
from pygra import meanfield
import os
g = geometry.honeycomb_lattice()
h0 = g.get_hamiltonian() # create hamiltonian of the system
ds = []
Us = np.linspace(0.0,3.0,10)
f = open("DELTA_VS_T_VS_MU.OUT","w")
h0.add_swave(0.0)
for U in Us:
h = h0.copy()
os.system("rm -rf *.pkl")
#scf = scftypes.attractive_hubbard(h,nk=10,mix=0.9,mf=None,g=-2.0,T=t)
mf = meanfield.guess(h,"random")
scf = meanfield.hubbardscf(h,nk=20,mix=0.9,U=-U,mf=mf,filling=0.1)
hscf = scf.hamiltonian
# rho = hscf.get_filling()
d = -np.mean(hscf.extract("swave").real)
f.write(str(U)+" ")
f.write(str(d)+"\n")
f.flush()
f.close()
# Add the root path of the pygra library import os ; import sys sys.path.append(os.path.dirname(os.path.realpath(__file__))+"/../../../src") import numpy as np from pygra import geometry from pygra import meanfield # this example performs a selconsistent calculation in a dimer g = geometry.lieb_lattice() # generate the geometry #g = g.supercell(2) mz = [] # lists to store magnetizations h = g.get_hamiltonian() # create hamiltonian of the system h.add_rashba(1.0) # add Rashba spin-orbit coupling #h.get_bands() ; exit() mf = meanfield.guess(h,mode="ferro") # antiferro initialization scf = meanfield.hubbardscf(h,filling=0.5,U=1.0,mf=mf,nk=5,verbose=1) # perform SCF scf.hamiltonian.write_magnetization(nrep=4) # write selfconsistent magnetization scf.hamiltonian.get_bands(operator="sz")
