The tube generates atomic positions of various nanotubes, such as carbon nanotube, h-BN, MoS$_2$, WS$_2$, and TiO$_2$ anatase (101) nanotubes [1-8].
Type make and run the code with the ./mktb command in the directories.
The setup.c file defines the Chiral index (n,m)=(10,4).
tb.n = 10; tb.m = 4;
You can generate (n, m) nanotube atomic coordinates by redefining the above index number.
The output file 'fig...vasp' is the atomic coordinates in VASP format. You can visualize these using the VESTA.
- fig1_sandbox.vasp : initial graphene sheet
- fig2_Ch-T-vectors.vasp : Chiral and translational vectors
- fig3_rotated-wall.vasp : rotated graphene
- fig4_cutout.vasp : cutout the graphene to make a wall of the tube
- fig5_tube.vasp : (n,m) nanotube
The file OMX.dat is the data file for the OpenMX, while the file QE.in is for the QuantumESPRESSO. Examples of band-structure calculations are saved in the omx-ex and qe-ex directories.
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Some of the metallic carbon nanotubes with small diameters open small energy gaps because of their steep curvature [1,2].
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You should manually optimize the supercell size to maintain accuracy and computational efficiency, especially for large-radius nanotubes, since the supercell dimensions are automatically set to 4 times the nanotube radius.
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The
c-ntdirectory contains a small Perl script, reset-positions.pl which resets the supercell dimensions as well as the axial position of the nanotube. -
Structural relaxations should be performed on some nanotubes before conducting band structure calculations. In our experiences, this procedure was quite essential for the anatase nanotubes.
If you encounter a multiple definition error during the GCC compilation, you can avoid it by adding the compile option -z muldefs in the Makefile.
You can refer to the Sec. 7.2 of the book, Computer simulation with C (Japanese), for more detail.
Reference
[1] S. Reich, C. Thomsen, and P. Ordejón, Phys. Rev. B, 65, 155411 (2002). https://doi.org/10.1103/PhysRevB.65.155411
[2] V. Zólyomi and J. Küriti, Phys. Rev. B, 70, 085403 (2004). https://doi.org/10.1103/PhysRevB.70.085403
[3] C. Jin, F. Lin, K. Suenaga, and S. Iijima, Phys. Rev Lett. 102, 195505 (2009). https://doi.org/10.1103/PhysRevLett.102.195505
[4] G. Y. Guo and J. C. Lin, Phys. Rev. B, 71, 165402 (2005). https://doi.org/10.1103/PhysRevB.71.165402
[5] G. Seifert, H. Terrones, M. Terrones, G. Jungnickel, and T. Frauenheim, Phys. Rev. Lett, 85, 146 (2000). https://doi.org/10.1103/PhysRevLett.85.146
[6] J. Xiao, M. Long, X. Li, H. Xu, H. Huang, and Y. Gao, Sci. Rep. 4, 4327 (2014). https://doi.org/10.1038/srep04327
[7] M. Ghorbani-Asl, N. Zibounche, M. Wahiduzzaman, A. F. Oliveira, A. Kuc, and T. Heine, Sci. Rep. 3, 2961 (2013). https://doi.org/10.1038/srep02961
[8] Francesca Nunzi and Filippo De Angelis, J. Phys. Chem C, 115, 2179 (2011). https://pubs.acs.org/doi/abs/10.1021/jp110132k