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TMDybinding

TMDybinding is an open-source Python module for pybinding. This package contains the basic lattices in the pybinding pb.Lattice() format to create tight-binding models for TMDs.

Installation

Installation is simple, just run 

pip install tmdybinding
The installation only contains the source files in the PyPi repository. This code does not need any compilation, this source can be used immediately in combination with pybinding.

Installing pybinding

Additionally, you might want to install the latest development version of pybinding. This latest version has additional tools to inspect the sublattices or orbitals, and analyze the wavefunction: 

pip install -i https://test.pypi.org/simple/ pybinding

Usage

Making a lattice

To use TMDybinding, first follow the tutorial at pybinding.

In TMDybinding, a pb.Lattice() is created for a specific TMD lattice. You need to make specific choices for the lattice you want to obtain:

  • params the parameters to use with the model
  • soc select if you want to include the spin orbit coupling (SOC)
  • material select the material you want to use (depends on the parameters of choice)
  • lat4 make a square unit cell (doubled to obtain the armchair direction)

For example, you can take the parameters from G-B. Liu for "MoS2" in a hexagonal lattice without SOC, for the specific model used in their publication for the sixth-nearest neighbour hopping (in their paper this is described as the third-nearest neighbour hopping, as they only consider the metal d-orbitals): 

import tmdybinding as tmdy

# make the lattice object
lat = tmdy.TmdNN256Me(params=tmdy.liu6["MoS2"]).lattice()

# make a figure with the lattice
lat.plot()

The lattice structure for the TMD.

Selecting parameters and classes

Please use the combinations of class and parameters as given in Documentation/Possible parameters.

Using the lattice

Below is a small example of how to use the code for the 5-band model from Liu/Wu: 

import pybinding as pb
import tmdybinding as tmdy

# get the parameters
lat = tmdy.TmdNN256Meo(params=tmdy.wu["MoS2"]).lattice()
model = pb.Model(lat, pb.translational_symmetry())
bz = lat.brillouin_zone()
bands = pb.solver.lapack(model).calc_bands(
    bz[3] * 0, bz[3], (bz[3] + bz[4]) / 2, bz[3] * 0
)
bands.plot(point_labels=[r"$\Gamma$", "$K$", "$M$", r"$\Gamma$"])

The band structure for the TMD.

Further documentation is coming soon. Made by Bert Jorissen.

Citing

If you used this code in your research, please cite the following article: B. Jorissen, L. Covaci, B. Partoens, SciPost Phys. Core 7, 004 (2024).