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Date: 2017/04/26 15:05
Name: mmhs

Dear all

I use openmx to calculate I-V characteristic of 2D nanosheet but i don not know how to choose a correct value for this parameter "NEGF.tran.Kgrid". Can anyone guide me to find a reliable value for this parameter?

When i performed the calculation
the current was (3.559753e-18 ampere) for "NEGF.tran.Kgrid 1 1" ,
and the current was (9.128436e-12 ampere) for "NEGF.tran.Kgrid 15 1".

Thanks in advance
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Re: NEGF.tran.Kgrid ( No.1 )
Date: 2017/04/26 19:05
Name: Artem Pulkin

"Can anyone guide me to find a reliable value for this parameter?"

Larger = better.
Re: NEGF.tran.Kgrid ( No.2 )
Date: 2017/04/26 23:29
Name: mmhs

Dear Artem Pulkin

But what is the optimum choice for this parameter in 2D nanosheet?
for example "NEGF.tran.Kgrid 30 1" is enough or too large?

Thanks for your reply
Re: NEGF.tran.Kgrid ( No.3 )
Date: 2017/04/26 23:52
Name: T. Ozaki


If your unit cell is narrow along the directions (b- and c-axes) perpendicular
to the transport direction (a-axis) and the bands along those directions are
dispersive, you need to take enough k-points to discretize the Brillouin zone.
Of course a proper choice depends on systems under study, and thereby systematic
benchmark calculations are required to see how quantities you want to calculate
converges as a function of the k-points.


Re: NEGF.tran.Kgrid ( No.4 )
Date: 2017/04/27 20:29
Name: Artem Pulkin

"But what is the optimum choice for this parameter in 2D nanosheet?"

I typically put 400 k-points for publication-quality figures. Sometimes, however, I am interested in high symmetry points only and 3 k-points per unit cell may be enough for me. As prof. Ozaki mentioned, you should adjust every parameter to your particular model and needs. I suggest to start with 20 k-points and double this value until you reach convergence in your I-V curve.
Re: NEGF.tran.Kgrid ( No.5 )
Date: 2017/04/28 02:37
Name: mmhs

Thanks for your help

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