Recent content by mohsen2002

Hi every one, I face with a question on my works, As you know there in many articles Physicist introduce a material that has zero gap without spin-orbit coupling (SOC). By applying the SOC, a relatively small gap (0.1 eV) is opened and it becomes topological insulator. My question, Is that...

Thank you so much for helpful discussion and your time.

Thank you for your reply. I can understand the gap, but is it match with our expectation of robustness of TI phase against interactions?

Hi every body, I faced a paradox. The topological insulator is robust against a potential that does not breaks the TRS. But in the original work of Kane-Mele (PRL 95, 146802), the "staggered sublattice potential" that does not breaks the TRS,, makes zigzag ribbon trivial insulator (figure 1 in...

Thanks for your reply, The effect of next nearest neighbor on the band structure is very small. My question is: Why the mail problem is around the Gama (Kx=Ky=0) point in FBZ? Here is a sample fitting for hexagonal Boron Nitride. (black line are DFT result and red line as a tight binding...

What is your purpose? Do you want calculate the tight binding parameters of the system? Perhaps i can help yu:shy:

I plot the tight binding bandstructure of graphene. There is a very good aggrement with ab-inition calculation in the valence band. but there is a problem in the non-localized orbitals of conduction band especially in the Gama(0,0) point. Any suggestion is appreciated.

the bandstructure is periodic in the inverse (fourier) space, but in the band structure is ploted in the first brillouin zone, by increasing the real space unit cell the inverse unit cell decreas. For plotting the new bandstructure you should move the old branch of bandstructure to new brillouin...

I asked a question about the calculaton of tight binding bandstructure in this froum (Tight Binding calculation of band structure), i think the answers are useful for you. in the tight binding the basis set for expanding the wave function are localized atomic robitals so the basis set dimension...

Thanks for your reply. I use this method for graphene (it is not easy) and it works properly. Thanks. Mohsen

Dear Saaskis, Thanks for your reply. could you please explain the exponential part of your reply or introduce a reference. I read Data, it only explain the subbands for nanotue. But i have problem with Graphene. Zone folding concept is fully explain for nanotubes, But i can not find a good...

Dear all, I want to calculate the band structure of graphene for a unit cell with 8 atoms in the Tight Binding approximation. There is no problem about drawing the band structure for a unit cell with 2 atoms. But by increasing the unit cell size, first brillouin decrease and there is a gap in...

I am sorry My English is poor

Hi OLD? I said it is new, I meant it is newer than other method(like decimiation) Ok

Hi I had your problem with surface green function, surface green's function calculation is the important part o coherent calculation There is some old method, there is a new method which is simple and effective see 'closed-form solutions to surface green's functions';'PHYSICAL REVIEW B vol55...