Subband structure of graphene nanoribbons: Difference between revisions

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==Tools==
==Tools==


* [https://wiki.fysik.dtu.dk/ase/ase/structure.html Create GNR atom coordinates using ASE]
* [https://wiki.fysik.dtu.dk/ase/ase/structure.html How to create GNR atom coordinates using ASE]


==8-ZGNR using grid==
==8-ZGNR using grid==
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<pre>
<pre>
from gpaw import GPAW, FermiDirac
from ase import Atoms
from ase.io import read, write
from gpaw import GPAW, PoissonSolver, Mixer
from ase.structure import graphene_nanoribbon
# -------------------------------------------------------------
# Bulk configuration
# -------------------------------------------------------------
zgnr = graphene_nanoribbon(8, 1, type='zigzag', saturated=True,
                            C_H=1.1, C_C=1.42086, vacuum=8.0,
                            magnetic=False, initial_mag=0.0)
zgnr.center()
write('zgnr.traj', zgnr)
# Make self-consistent calculation and save results
calc = GPAW(h=0.18,
            mode='fd',
            xc='PBE',
            kpts=(1,1,9),
            maxiter=600,
            occupations=FermiDirac(width=0.05, maxiter=2000),
            mixer=Mixer(beta=0.010, nmaxold=8, weight=100.0),
            poissonsolver=PoissonSolver(eps=1e-12),
            txt='band_sc.txt')
zgnr.set_calculator(calc)
zgnr.get_potential_energy()
calc.write('band_sc.gpw')
# Calculate band structure along Gamma-X
from ase.dft.kpoints import ibz_points, get_bandpath
#points = ibz_points['fcc']
#G = points['Gamma']
#X = points['X']
G = (0, 0, 0)
X = (0, 0, 0.5)
kpts, x, X = get_bandpath([G, X], zgnr.cell, 60)
calc = GPAW('band_sc.gpw',
            mode='fd',
            kpts=kpts,
            txt='band_harris.txt',
            fixdensity=True,
            maxiter=600,
            parallel={'domain': 1},
            eigensolver='cg', # 'cg' is allowed for grid method only
            usesymm=None,
            convergence={'bands': 100})
#          convergence={'bands': 'all'})
if calc.input_parameters['mode'] == 'lcao':
    calc.scf.reset()
calc.get_potential_energy()
ef = calc.get_fermi_level()
calc.write('band_harris.gpw')
calc = GPAW('band_harris', txt=None)
import numpy as np
eps_skn = np.array([[calc.get_eigenvalues(k,s)
                    for k in range(60)]
                    for s in range(1)]) - ef
# Write the results to a file for plotting with some external package
f = open('bands.dat', 'w')
for n in range(66):
    for k in range(60):
        print >>f, k, eps_skn[0, k, n]
    print >>f


</pre>
</pre>
Line 20: Line 98:
from ase.io import read, write
from ase.io import read, write
from gpaw import GPAW, PoissonSolver, Mixer
from gpaw import GPAW, PoissonSolver, Mixer
from ase.structure import graphene_nanoribbon  
from ase.structure import graphene_nanoribbon




Line 53: Line 131:
# Calculate band structure along Gamma-X  
# Calculate band structure along Gamma-X  
from ase.dft.kpoints import ibz_points, get_bandpath
from ase.dft.kpoints import ibz_points, get_bandpath
#points = ibz_points['fcc']
#G = points['Gamma']
#X = points['X']
G = (0, 0, 0)
G = (0, 0, 0)
X = (0, 0, 0.5)
X = (0, 0, 0.5)
Line 75: Line 150:


calc.get_potential_energy()
calc.get_potential_energy()
ef = calc.get_fermi_level()
calc.write('band_harris.gpw')
calc.write('band_harris.gpw')
</pre>
calc = GPAW('band_harris', txt=None)
import numpy as np
 
eps_skn = np.array([[calc.get_eigenvalues(k,s)
                    for k in range(60)]
                    for s in range(1)]) - ef
 
 


*find_band_as_dat.py
# Write the results to a file for plotting with some external package
<pre>
f = open('bands.dat', 'w')
for n in range(66):
    for k in range(60):
        print >>f, k, eps_skn[0, k, n]
    print >>f


</pre>
</pre>

Latest revision as of 15:47, 17 November 2014

Tools

8-ZGNR using grid

  • zgnr_grid.py:
from gpaw import GPAW, FermiDirac
from ase import Atoms
from ase.io import read, write
from gpaw import GPAW, PoissonSolver, Mixer
from ase.structure import graphene_nanoribbon


# -------------------------------------------------------------
# Bulk configuration
# -------------------------------------------------------------

zgnr = graphene_nanoribbon(8, 1, type='zigzag', saturated=True,
                            C_H=1.1, C_C=1.42086, vacuum=8.0,
                            magnetic=False, initial_mag=0.0)

zgnr.center()
write('zgnr.traj', zgnr)


# Make self-consistent calculation and save results
calc = GPAW(h=0.18,
            mode='fd',
            xc='PBE',
            kpts=(1,1,9),
            maxiter=600,
            occupations=FermiDirac(width=0.05, maxiter=2000),
            mixer=Mixer(beta=0.010, nmaxold=8, weight=100.0),
            poissonsolver=PoissonSolver(eps=1e-12),
            txt='band_sc.txt')

zgnr.set_calculator(calc)
zgnr.get_potential_energy()
calc.write('band_sc.gpw')


# Calculate band structure along Gamma-X 

from ase.dft.kpoints import ibz_points, get_bandpath
#points = ibz_points['fcc']
#G = points['Gamma']
#X = points['X']
G = (0, 0, 0)
X = (0, 0, 0.5)
kpts, x, X = get_bandpath([G, X], zgnr.cell, 60)

calc = GPAW('band_sc.gpw',
            mode='fd',
            kpts=kpts,
            txt='band_harris.txt',
            fixdensity=True,
            maxiter=600,
            parallel={'domain': 1},
            eigensolver='cg', # 'cg' is allowed for grid method only
            usesymm=None,
            convergence={'bands': 100})
#           convergence={'bands': 'all'})
if calc.input_parameters['mode'] == 'lcao':
    calc.scf.reset()

calc.get_potential_energy()
ef = calc.get_fermi_level()
calc.write('band_harris.gpw')

calc = GPAW('band_harris', txt=None)
import numpy as np

eps_skn = np.array([[calc.get_eigenvalues(k,s)
                     for k in range(60)]
                    for s in range(1)]) - ef



# Write the results to a file for plotting with some external package
f = open('bands.dat', 'w')
for n in range(66):
    for k in range(60):
        print >>f, k, eps_skn[0, k, n]
    print >>f

8-ZGNR using LCAO

  • zgnr_lcao.py:
from gpaw import GPAW, FermiDirac
from ase import Atoms
from ase.io import read, write
from gpaw import GPAW, PoissonSolver, Mixer
from ase.structure import graphene_nanoribbon


# -------------------------------------------------------------
# Bulk configuration
# -------------------------------------------------------------

zgnr = graphene_nanoribbon(8, 1, type='zigzag', saturated=True,
                            C_H=1.1, C_C=1.42086, vacuum=8.0,
                            magnetic=False, initial_mag=0.0)

zgnr.center()
write('zgnr.traj', zgnr)


# Make self-consistent calculation and save results
calc = GPAW(h=0.18,
            mode='lcao',
            xc='PBE',
            basis='szp(dzp)',
            kpts=(1,1,9),
            occupations=FermiDirac(width=0.05, maxiter=2000),
            mixer=Mixer(beta=0.010, nmaxold=8, weight=100.0),
            poissonsolver=PoissonSolver(eps=1e-12),
            txt='band_sc.txt')

zgnr.set_calculator(calc)
zgnr.get_potential_energy()
calc.write('band_sc.gpw')


# Calculate band structure along Gamma-X 
from ase.dft.kpoints import ibz_points, get_bandpath
G = (0, 0, 0)
X = (0, 0, 0.5)
kpts, x, X = get_bandpath([G, X], zgnr.cell, 60)

calc = GPAW('band_sc.gpw',
            mode='lcao',
            xc='PBE',
            basis='szp(dzp)',
            kpts=kpts,
            txt='band_harris.txt',
            fixdensity=True,
            parallel={'domain': 1},
            usesymm=None,
            convergence={'bands': 'all'})

if calc.input_parameters['mode'] == 'lcao':
    calc.scf.reset()

calc.get_potential_energy()
ef = calc.get_fermi_level()
calc.write('band_harris.gpw')
calc = GPAW('band_harris', txt=None)
import numpy as np

eps_skn = np.array([[calc.get_eigenvalues(k,s)
                     for k in range(60)]
                    for s in range(1)]) - ef



# Write the results to a file for plotting with some external package
f = open('bands.dat', 'w')
for n in range(66):
    for k in range(60):
        print >>f, k, eps_skn[0, k, n]
    print >>f