1

##### Questions and Answers / Re: Interface Builder

« Last post by**Dipankar Saha**on

*»*

**Today**at 17:03Yes... / Thank you Ulrik !

1

Yes... / Thank you Ulrik !

2

Thanks again for your great suggestion. I will run the previous scripts with high symmetry points.

Actually, my script is related to strained (2*2) Graphene. Because I firstly built an interface between SiC and Graphene and then remove the SiC. In this process Graphene was under strain around 8% and I think this value of gap came from strained Graphene.

Actually, my script is related to strained (2*2) Graphene. Because I firstly built an interface between SiC and Graphene and then remove the SiC. In this process Graphene was under strain around 8% and I think this value of gap came from strained Graphene.

3

The rotation matrix is defined in equation 4 of the paper, and describes how B* is rotated to match up u_1 and v_1 - the strain tensor then describes how the length of the supercell lattice vectors must change, in order to be equal.

4

Dear all

I have a question about Spin-orbit coupling. When i calculate the SOC, i am not sure how to set the initial state? Whether the initial spin state is necessarily related to SOC?

Thanks all.

I have a question about Spin-orbit coupling. When i calculate the SOC, i am not sure how to set the initial state? Whether the initial spin state is necessarily related to SOC?

Thanks all.

5

Is there any relation between 'rotation matrix' and 'strain tensor' ? If not, then what's the role of 'rotation matrix'?

6

For pristine graphene, you should have zero gap at the K point. In your calculations without the SOC included, you seem to get an ultra-small gap value within numerical noise or calculation error. Also, one would really have to choose a proper k-point grid, not only in terms of k-grid density - the grid should include K, M and G symmetry points, see discussion in Appendix in this paper, Phys. Rev. B 87, 075414 (2013).

The same holds true when you include SOC, the computational settings (k-grid, mesh density and so on) must be chosen carefully. It is just my personal opinion, but this tiny SOC-induced gap in graphene does not seem to be very relevant (even at quite low temperatures), unless somebody shows me a particular example where it does.

The same holds true when you include SOC, the computational settings (k-grid, mesh density and so on) must be chosen carefully. It is just my personal opinion, but this tiny SOC-induced gap in graphene does not seem to be very relevant (even at quite low temperatures), unless somebody shows me a particular example where it does.

7

Thanks Petr for your help.

I have another question. I obtained the bandgap of the structure with and without SO interaction. The bandgap value is 0.0001964eV when SOI is not considered. It then decreases to 0.0001564eV when SOI is considered. As far as I know when we consider SOI the bandgap should increase not decrease. I attached again my scripts.

I have another question. I obtained the bandgap of the structure with and without SO interaction. The bandgap value is 0.0001964eV when SOI is not considered. It then decreases to 0.0001564eV when SOI is considered. As far as I know when we consider SOI the bandgap should increase not decrease. I attached again my scripts.

8

thank you for your kindly reply,but transmission pathways can only get the direction of current flow between atoms? how the interference can be analyzed

It depends on what you mean by interference analysis. You might for example look at the Transmission Eigenstates (2D or 3D wave function image), https://docs.quantumwise.com/manual/Types/TransmissionEigenstate/TransmissionEigenstate.html. But it is really up to you to decide on what kind of physical quantities you want to study in the numerical calculations. We can then advise you if that particular quantity can be computed in QuantumATK.

in fact, i want to know there is a destructive quantum inertereface or not.

i saw some paper, including the paper listed in the website of about transmission pathways, said if there is a ring current, it means there is a destructive. but it is only valid for the ring structures. for the linear structures, how can i know:)

9

Thank you for the feedback. Please could you give us 2 examples where you encountered (1) 404 error, and (2) redirection to www.synopsys.com instead of the actual QuantumATK page, https://www.synopsys.com/silicon/quantumatk.html?

10

You may use the IVCharacteristics study object for being able to do an easy restart, see https://docs.quantumwise.com/tutorials/ivcharacteristics/ivcharacteristics.html and https://docs.quantumwise.com/webinars/webinars.html#new-framework-for-iv-curve-simulations.