Band structure with DFTB (SCC-DFTB, GFN1-xTB)¶
Metal band structure with SCC-DFTB¶
Build the primitive Cu unit cell:
from scm.plams import view
from scm.base import ChemicalSystem
from ase.build import bulk
Cu = ChemicalSystem.from_ase_atoms(bulk("Cu", "fcc", a=3.6)) # primitive cell
view(Cu, width=150, height=150, show_atom_labels=True)
Single-point calculation with SCC-DFTB and parameters
DFTB.org/matsci-0-3:
from scm.plams import Settings, AMSJob
s = Settings()
s.input.ams.Task = "SinglePoint"
s.input.DFTB.Periodic.BandStructure.Enabled = "Yes"
s.input.DFTB.Model = "SCC-DFTB"
s.input.DFTB.ResourcesDir = "DFTB.org/matsci-0-3"
s.runscript.nproc = 1
job = AMSJob(settings=s, name="Cu", molecule=Cu)
job.run();
[09.02|14:20:41] JOB Cu STARTED
[09.02|14:20:41] Renaming job Cu to Cu.004
[09.02|14:20:41] Job Cu.004 previously run as Cu, using old results
[09.02|14:20:41] JOB Cu.004 COPIED
from scm.plams.tools.plot import plot_band_structure
import matplotlib.pyplot as plt
x, y_spin_up, y_spin_down, labels, fermi_energy = job.results.get_band_structure(
unit="eV"
)
ax = plot_band_structure(x, y_spin_up, None, labels, fermi_energy, zero="fermi")
ax.set_ylim(-10, 10)
ax.set_ylabel("$E - E_{Fermi}$ (eV)")
ax.set_xlabel("Path")
ax.set_title("Cu with DFTB.org/matsci-0-3")
ax;
Semiconductor band structure with GFN-1xTB¶
For a semiconductor like ZnO you can also choose to put the zero at the VBM (‘vbm’) or CBM (‘cbm’)
from scm.plams import view
from scm.base import ChemicalSystem
from ase.build import bulk
ZnO = ChemicalSystem.from_ase_atoms(bulk("ZnO", "wurtzite", a=3.2, c=5.3, u=0.375))
ZnO.guess_bonds() # doesn't affect DFTB, just helps visualization
view(ZnO, direction="corner_z", width=300, height=300, show_atom_labels=True)
from scm.plams import Settings, AMSJob
s = Settings()
s.input.ams.Task = "SinglePoint"
s.input.DFTB.Periodic.BandStructure.Enabled = "Yes"
s.input.DFTB.Model = "GFN1-xTB"
s.runscript.nproc = 1
job = AMSJob(settings=s, molecule=ZnO, name="ZnO")
job.run();
[09.02|14:21:02] JOB ZnO STARTED
[09.02|14:21:02] JOB ZnO RUNNING
[09.02|14:21:06] JOB ZnO FINISHED
[09.02|14:21:06] JOB ZnO SUCCESSFUL
The below call to plot_band_structure plots both the spin up and
spin down. The spin-down bands are plotted as dashed lines. Note that in
this case there is no spin polarization so the spin-down bands perfectly
overlap the spin-up bands.
# get_band_structure returns an axis in AMS2025+
ax = plot_band_structure(*job.results.get_band_structure(unit="eV"), zero="vbmax")
ax.set_ylim(-10, 10)
ax.set_ylabel("$E - E_{VBM}$ (eV)")
ax.set_xlabel("Path")
ax.set_title("ZnO with GFN1-xTB")
ax;
See also¶
Python Script¶
#!/usr/bin/env python
# coding: utf-8
# ## Metal band structure with SCC-DFTB
# Build the primitive Cu unit cell:
from scm.plams import view
from scm.base import ChemicalSystem
from ase.build import bulk
Cu = ChemicalSystem.from_ase_atoms(bulk("Cu", "fcc", a=3.6)) # primitive cell
view(Cu, width=150, height=150, show_atom_labels=True, picture_path="picture1.png")
# Single-point calculation with SCC-DFTB and parameters `DFTB.org/matsci-0-3`:
from scm.plams import Settings, AMSJob
s = Settings()
s.input.ams.Task = "SinglePoint"
s.input.DFTB.Periodic.BandStructure.Enabled = "Yes"
s.input.DFTB.Model = "SCC-DFTB"
s.input.DFTB.ResourcesDir = "DFTB.org/matsci-0-3"
s.runscript.nproc = 1
job = AMSJob(settings=s, name="Cu", molecule=Cu)
job.run()
from scm.plams.tools.plot import plot_band_structure
import matplotlib.pyplot as plt
x, y_spin_up, y_spin_down, labels, fermi_energy = job.results.get_band_structure(unit="eV")
ax = plot_band_structure(x, y_spin_up, None, labels, fermi_energy, zero="fermi")
ax.set_ylim(-10, 10)
ax.set_ylabel("$E - E_{Fermi}$ (eV)")
ax.set_xlabel("Path")
ax.set_title("Cu with DFTB.org/matsci-0-3")
ax
ax.figure.savefig("picture2.png")
# ## Semiconductor band structure with GFN-1xTB
#
# For a semiconductor like ZnO you can also choose to put the zero at the VBM ('vbm') or CBM ('cbm')
from scm.plams import view
from scm.base import ChemicalSystem
from ase.build import bulk
ZnO = ChemicalSystem.from_ase_atoms(bulk("ZnO", "wurtzite", a=3.2, c=5.3, u=0.375))
ZnO.guess_bonds() # doesn't affect DFTB, just helps visualization
view(ZnO, direction="corner_z", width=300, height=300, show_atom_labels=True, picture_path="picture3.png")
from scm.plams import Settings, AMSJob
s = Settings()
s.input.ams.Task = "SinglePoint"
s.input.DFTB.Periodic.BandStructure.Enabled = "Yes"
s.input.DFTB.Model = "GFN1-xTB"
s.runscript.nproc = 1
job = AMSJob(settings=s, molecule=ZnO, name="ZnO")
job.run()
# The below call to ``plot_band_structure`` plots both the spin up and spin down. The spin-down bands are plotted as dashed lines. Note that in this case there is no spin polarization so the spin-down bands perfectly overlap the spin-up bands.
# get_band_structure returns an axis in AMS2025+
ax = plot_band_structure(*job.results.get_band_structure(unit="eV"), zero="vbmax")
ax.set_ylim(-10, 10)
ax.set_ylabel("$E - E_{VBM}$ (eV)")
ax.set_xlabel("Path")
ax.set_title("ZnO with GFN1-xTB")
ax
ax.figure.savefig("picture4.png")