Re: [Kwant] Building tight binding Hamiltonian with multi atom with multi-orbital basis

Dear Santu, Simply use 4 x 4 matrices instead of 2 x 2 matrices and it shall work. Best, Xavier

Le 24 janv. 2018 à 03:42, Santu Baidya a écrit :

First of all thank you very much for your reply. I have been trying to follow your suggestions. Somehow I can not get it. Sorry for this. However, according to the manual, the Hopping kind is defined only between sites, (not orbitals !) as mentioned on page no. 28.

" A hopping is defined using two sites. If several hoppings are added at once, these two sites should be encapsulated in a tuple. In particular, one must write: syst[((lat(0,j+1), lat(0, j)) for j in range(W-1)] = ... " To make a multi-orbital Hamiltonian one needs hopping from more than two orbital of one site to more than two orbital of another site. Please give me one small documentation of such situation. For example A site (px) to B site ( py) and B site (px) to A site (py).

The example you gave about spin_orbit.py, there is the definition of sigma_0,1,2 Pauli spin matrix only 2by2 matrices. If I want 4 orbital tight binding Hamiltonian what about then.

Please tell me about this.

Thanking you,

Santu Baidya

On 22 January 2018 at 19:30, Antonio Lucas Rigotti Manesco mailto:antoniolrm@usp.br> wrote: Santu,

Take a look at the graphene tutorial for honeycomb: https://kwant-project.org/doc/1/tutorial/graphene https://kwant-project.org/doc/1/tutorial/graphene In order to add orbital degrees of freedom you need to introduce a spinor notation as the superconducting example: https://kwant-project.org/doc/1/tutorial/superconductors https://kwant-project.org/doc/1/tutorial/superconductors Best,

Em seg, 22 de jan de 2018 08:15, Santu Baidya mailto:santubaidya2009@gmail.com> escreveu: Dear Kwang users,

I have recently started using Kwant for making model Hamiltonian. It is really very good python package. I have started learning some tutorials. I would like to know if making tight-binding Hamiltonian with multi atom and multi orbital basis possible using Kwant. I can not find such example in documentation. I would like to then try to make a honeycomb lattice with two atoms and each atom with two basis, e.g., px, py.

Please help me to know about this in more detail. Thanking you,

Santu B

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