QuantumATK Forum

QuantumATK => General Questions and Answers => Topic started by: postnikov on July 1, 2010, 10:11

Title: LiH2 gated method
Post by: postnikov on July 1, 2010, 10:11

Thanks!


I perform one test calculation using the Li-H2 system. The gate voltage is varied from 0.0 to 6.0, however, I find the corresponding T(E) varies very small. The T(E)  and  the input files the case of gate 6.0 and 2.0 are attached.

My calculations are right?

I am sorry that I can't post this via one new topic, since the system always tells me I have posted it.

Title: Re: LiH2 gated method
Post by: Anders Blom on July 1, 2010, 10:16

Probably that's correct, I don't expect a large variation due to the large HOMO-LUMO gap (and the simplicity) of the H2 molecule in the middle.

Title: Re: LiH2 gated method
Post by: postnikov on July 1, 2010, 10:22

“the large band gap (and the simplicity) of the H2 molecule in the middle”

You mean that the HOMO-LUMO gap is very big for the H2 molecule, and then the effect of the energy level shift  via gate voltage is very small?

If the gap is small for the molecule in the scattering reion, the effect of gate voltage should be very big?

Title: Re: LiH2 gated method
Post by: Anders Blom on July 1, 2010, 10:26

Well the way the "gate" works is to move the Fermi level of the atoms you project it on. So if the HOMO-LUMO gap is large, moving the Fermi energy has no real effect. Besides, the Li-H2 system is a toy model so it's hard to extract any real physics from it...

What you can use the gate for, for a more realistic system, is to simulate the effect of a gate (naturally) the influence of which is to charge the central region (positive or negative).

Also note that in ATK 10.8 you can insert real metal gates and dielectric screening regions, allowing for a much more realistic gate electrode effect.