1. VIRTUAL NANOLAB BY QUANTUMWISE
Presentation by:
Sheng Yu
Supervisor: Prof. Qiliang Li

2. Outline: 2. MoS2 monolayer (1) Build structure
1. Download and install Virtual NanoLab
2. MoS2 monolayer
(1) Build structure
(2) Optimize the structure
(3) Change your unit cell
(4) Simulate your structure
(5) Analyze your results
3. IV curve for MoS2 nanoribbon

3. Installation
1. TRIAL LICENSE

4. 2. DOWNLOAD
3. Installation

6. Manual for installation
/InstallationGuide.pdf

7. 2. Simulation on MoS2 monolayer
(1) Build your own structure.
① Jobs command window ② The jobs you have already finished
③ The jobs you are going to analyze ④ Analysis window

9. Find your crystal
Unit cell of 3D MoS2

10. Drag to select right 3 atoms,
Press Delete.

11. Press Ctrl + R: Stretch the unit cell ● Increasing the separation
between neighboring layers
Press Ctrl + R:
(Make the unit cell in the central window)

12. Center the atoms in the central
simulation box
The unit cell of 2D MoS2 monolayer

13. Important! Change your lattice type back into Hexagonal
●Unit cell: the simulation box composes the whole structure.
●Hexagonal: the simulation box repeats infinitely in Hexagonal route.

14. (2) Optimize your structure
Go to Script Generator

15. Due to 2D nature in A,B direction
K-point Sampling
nA=9 nB=9 nC=1,
Due to 2D nature in A,B direction
Spin: Unpolarized (No energy level separation)
Polarized (The energy level separation
in valence band)

16. Do not constrain cell
Save your Job

17. Run it!

18. (3) Change your unit cell
● Changing unit cell is for better later simulation and results display.
● Changing unit cell do not means changing the lattice structure.
Drag your structure
into Builder

19. Change the supercell (Coordinate vector)
●Make it into rectangular coordinate
Swap Axes
●Make it more transparent appearance

20. Center your atoms in the simulation box
Press Ctrl + R:

21. Important! Change your lattice type into Simple orthorhombic
● Simple orthorhombic is for rectangular box.

22. (4) Simulate your structure
Go to Script Generator
Add your items.
● Physical properties you are interested.

23. K-point Sampling
nA=1 nB=9 nC=9,
Due to 2D nature in B, C direction

24. K space route:
G, Y, Z, G
● G(0,0,0)
● Y(0,1,0)
● Z(0,0,1)
● Do not add X(1,0,0)
due to 2D nature in B,C direction

26. (5) See your simulation results!

27. Band structure for monolayer MoS2
Density of states for monolayer MoS2

28. Chemical potential for monolayer MoS2
Electron density for monolayer MoS2

29. Effective mass

30. Effective mass Direction: [0, 1, 0]: zigzag [0, 0, 1]: armchair
Relative band index:
0: Electrons
-1: Holes
Drag your nc file into Effective Mass Box

31. 3. IV curve for MoS2 nanoribbon
Repeat unit cell 5×9
● Make it into nanoribbon
Add electrodes

32. Device structure
Go to Script Generator

33. Choose:
New Calculator
Transmission Spectrum
1st New Calculator:
K-points 1×1×50
Bias voltage: 0.01V

34. Increase Maximum steps to 1000
● Assure Converging

35. Set the boundary condition:
Periodic
Dirichlet: The electric potential continues at the boundary
Neumann: The electric field continues at the boundary

36. For the 2ND New Calculator,
set the same parameters but different
electrode voltage: 0.02V
Save and Run!

37. See your results
Your results in Window 3
See your results

38. Drag your nc file into I-V Curve box

39. Your results:
● Transmission Spectrum
● Current vs. Voltage
Calculated by non-equilibrium Greens function (NEGF)

40. Transmission spectrum of perfect sheets of graphene and MoS2:
Opening a band gap in silicene and bilayer graphene with an electric field:
Effective mass of electrons in silicon:
Sheng Yu
Phone number:
Engineering Building 2602