Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.


Messages - Dongzhe

Pages: [1]
1
Questions and Answers / Re: Zero Bias Transmission
« on: June 10, 2021, 19:41 »
Hi Sumit,

To calculate the zero-bias T(E), you can either use the wavefunction-matching approach (e.g., PWCOND code) or Green's function-based method (e.g., QuantumATK, TranSIESTA...).

If u use the latter approach, once you have the Hamiltonian and overlap matrices from DFT, you can, in principle, calculate the T(E) without iterating the Green's function (i.e., equilibrium density matrix). However, in most NEGF codes, we do the Green's function iteration anyway for zero-bias because the periodic DFT solution might differ from the NEGF one.

I hope this answers your question.
Best regards,
Dongzhe

2
Dear ATK experts,

As a new user, I have a basic question concerning the symmetry operations for the nb of irreducible k-points.

I just runned the test example of Si bulk with 9x9x9 k-points (see the basic parameters below), however, the code only detects the time-reversal symmetry, thus Number of irreducible k-points: 365...

Can u explain why?

Thanks,
Dongzhe

PS: If I specify explicitly in MPgrid the symmetries by hand, I can reduce the k but this is rather impractical.

----------------------------
# Set up lattice
lattice = FaceCenteredCubic(5.4306*Angstrom)

# Define elements
elements = [Silicon, Silicon]

# Define coordinates
fractional_coordinates = [[ 0.  ,  0.  ,  0.  ],
                          [ 0.25,  0.25,  0.25]]

k_point_sampling = MonkhorstPackGrid(
    na=9,
    nb=9,
    nc=9,
    )
------------------------

Pages: [1]