______                         ______  ____
               /\__  _\            __         /\__  _\/\  _`\
               \/_/\ \/ __  __  __/\_\    ____\/_/\ \/\ \ \L\ \
                  \ \ \/\ \/\ \/\ \/\ \  /',__\  \ \ \ \ \  _ <'
                   \ \ \ \ \_/ \_/ \ \ \/\__, `\  \ \ \ \ \ \L\ \
                    \ \_\ \___x___/'\ \_\/\____/   \ \_\ \ \____/
                     \/_/\/__//__/   \/_/\/___/     \/_/  \/___/

TwisTB

This GitHub repository hosts the MATLAB codes developed at University of Trieste and Imperial College for the calculation of the structural and electronic properties of twisted homo- and hetero- multilayer of different transition metal dichalcogenides.

Authors

• Valerio Vitale (MATLAB codes for the generation of inital structures)
• Valerio Vitale and Kemal Atalar (MATLAB codes for tight-binding calculations of twisted bilayer TMDs)

In publications arising from using this code please cite:

Vitale, V., Atalar, K., et al. 2D Mater. 8 045010 (2021)

ASG - Atomic Structures Generator

Author

Valerio Vitale, University of Trieste

• Email: vitale.valerio .at. units.it

Description

This module is a suite of MATLAB codes to generate the atomic structures of twisted homo- and hetero-bilayers of 2D materials with a hexagonal unit cell, e.g. graphene, hBN, TMDs. The input parameters can be specified in the main.m MATLAB file, both for homo and hetero bilayers. Several files can be generated:

1. <rootname>.xyz or <rootname>.xsf file for visualisation purposes
2. lammps_positions.<rootname>.dat file to be used as input file for LAMMPS

Usage

You must have a MATLAB installed on your machine.

1. In MATLAB

• Change directory working directory to the one containing the main.m file relative to the system of interest (e.g. homobilayer)
• Simply type main in MATLAB Command Window
• Your output files can be found in your working directory

2. From terminal

• Open a new terminal window
• Change directory to the one containing the main.m relative to the system of interest (e.g. homobilayer)
• Type the following command: $> matlab -nodisplay -nodesktop -nojvm -r "main ;exit"
• Your output files can be found in your working directory

Notes

For twisted homo-bilayers, e.g. twisted bilayer graphene (TBLG), the twist angle is specified by a pair of integers (n,m). The commensurate Moirè lattice is constructed from n,m and the lattice parameter of the single layer. The resulting Moirè cell is also hexagonal. A description of the input file is given in the header of the main.m file

For twisted hetero-bilayers, e.g. graphene on hBN, one has to specify a target angle and the ratio of the two lattice parameters. A description of the input parameters is given in the header of the main.m file

TB - Tight-Binding

To use the tight-binding code you need to create an input file (see the header in the read_input.m routine)

Funding:

This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement no. 101067977